- Glossary -

Accelerator key – A key combination that provides access to a menu choice, macro, or other function of the application in lieu of selection with the mouse, usually combining Alt+key. Sometimes called a shortcut key, but shortcut keys usually consist of Ctrl+key combinations.

Access Developer's Toolkit – See ADT.

Activation – An OLE 2.0 term meaning to place an object in a running state, which includes binding the object, or to invoke a method of the object. See also Binding.

Active – In Windows, the currently running application or the window to which user input is directed; the window with the focus. See also Focus.

Add-in – Visual Basic add-ins are OLE client applications that manipulate Visual Basic 4.0's development environment whose objects are exposed by a reference to the Vbext32.olb type library. Add-ins are capable of adding custom items to Visual Basic 4.0's menus, to manipulate the active form and controls, and to respond to file control events.

Address – The numerical value, usually in hexadecimal format, of a particular location in your computer's random-access memory (RAM).

ADT – Abbreviation for the Access Developer's Toolkit that allows distribution of Msaccess.exe and other files needed to run (but not design) Access 95 applications. The ADT includes a Setup Wizard to create distribution diskettes for Access run-time applications and several 32-bit OLE Controls that also are distributed with Visual Basic 4.0. (Prior versions of the ADT included a run-time Access executable, MSARN?00.EXE. Access 95 uses the retail executable, Msaccess.exe, and an entry in the Registry to disable design-mode features.)

Aggregate functions – The ANSI SQL functions AVG(), SUM(), MIN(), MAX(), and COUNT() and Access SQL functions StDev(), Var(), First(), and Last(). Aggregate functions calculate summary values from a group of values in a specified column. They are usually associated with GROUP BY and HAVING clauses. See also Domain aggregate functions.

Aggregate object – An OLE 2.0 term that refers to an object class that contains one or more member objects of another class.

Alias – A temporary name assigned to a table in a self join, to a column of a query, or to rename a table, implemented by the AS reserved word in ANSI SQL. Alias is also an embedded keyword option for the Declare statement. The Alias keyword is used to register prototypes of DLL functions so that the function can be called from programs by another name. Aliasing the ANSI versions of 32-bit Windows API functions to function names without the "A" suffix is common when writing common code for 16-bit and 32-bit applications.

ANSI – An abbreviation for the American National Standards Institute. ANSI in the Windows context refers to the ANSI character set that Microsoft decided to use for Windows (rather than the IBM PC character set that includes special characters such as those used for line drawing, called the OEM character set). The most common character set is ASCII (the American Standard Code for Information Interchange), which for English alphabetic and numeric characters, is the same as ANSI. Windows 95 and Windows NT include both ANSI (suffix "A") and Unicode (suffix "W") versions of Windows API functions. See ASCII and Unicode.

API – An abbreviation for Application Programming Interface. Generically, a method by which a program can obtain access to or modify the operating system. In 32-bit Windows, the 1,000 or so functions provided by Windows 95 and Windows NT DLLs that allow applications to open and close windows, read the keyboard, interpret mouse movements, and so on. Programmers call them hooks. VBA provides access to these functions with the Declare statement. See also DLL.

Applet – A Windows application that is supplied as a component of another Windows application, rather than a retail product. The Notepad, Wordpad, and Character Map applications supplied with Windows 95 are examples of applets.

Application – The software product that results from creation of a program, often used as a synonym for the programming (source) code that creates it. Microsoft Word, Microsoft Excel, WordPerfect for Windows, and Lotus 1-2-3 are called mainstream Windows productivity applications in this book. Applications are distinguished by the environment for which they are designed (for example, Windows, DOS, Macintosh, UNIX) and their purpose. Windows applications carry the DOS executable file extension, .exe.

Application Close button – The small, square button with an "X" caption at the extreme right of the title bar of an application running in Windows 95. Clicking the Application Close button closes the running application.

Application Control menu box – The small, square button with a miniature application icon at the extreme left of the title bar of an application. Clicking the Application Control menu box displays the Application Control menu. Double-clicking the Application Control menu box closes the application.

Argument – Data supplied to a function and upon which the function acts or uses to perform its task. Arguments are enclosed in parentheses. Additional arguments, if any, are separated by commas. Arguments passed to procedures usually are called parameters.

Array – An ordered sequence of values (elements) stored within a single named variable, accessed by referring to the variable name with the number of the element (index or subscript) in parentheses, as in strValue = strArray(3). Arrays in VBA may have more than one dimension, in which case, access to the value includes indexes for each dimension, strValue = strArray(3,3).

ASCII – Abbreviation for the American Standard Code for Information Interchange. A set of standard numerical values for printable, control, and special characters used by PCs and most other computers. Other commonly used codes for character sets are ANSI (used by Windows 3.1+), Unicode (used by Windows 95 and Windows NT), and EBCDIC (Extended Binary-Coded Decimal Interchange Code, used by IBM for mainframe computers.) See Unicode.

Assign – To give a value to a named variable.

Attached table – A table that is not stored in the currently open Jet database (native or base table), but which you can manipulate as if the table were a native table. In Access 95 terminology, an attached table is a linked table. See Linked table.

Asynchronous – A process that can occur at any time, regardless of the status of the operating system or applications that are running.

Authentication – The process of verifying a user's login ID and password.

Automation – An OLE 2.0 term that refers to a means of manipulating another application's objects. See also OLE Automation.

Automation client – An OLE 2–compliant Windows applications with an application programming (macro) language, such as VBA, that is capable of referencing and manipulation of objects exposed by OLE Automation servers.

Automation server – Technically, any OLE 2–compliant Windows application that supports OLE Automation operations by exposing a set of objects for manipulation by OLE Automation client applications. This book restricts the term automation server to applications that are not OLE 2+ full servers but expose application objects. Access 95 is an example of an automation server.

AutoNumber – An Jet 3.0 replacement for the Counter field data type of Jet 1.x and 2.0. AutoNumber fields may be of the Increment or Random type. Fields of the Increment AutoNumber field data type usually are used to create primary keys in cases where an unique primary key cannot be created from data in the table.

Back up – To create a file (backup file) that duplicates data stored in one or more files on a client or server computer.

Background – In multitasking computer operations, the application or procedure that is not visible on-screen and that does not receive user generated input. In Windows, an application that is minimized and does not have the focus is in the background.

Base date – A date used as a reference from which other date values are calculated. In the case of VBA and SQL Server, the base date is January 1, 1900.

Base tables – The permanent tables from which a query is created. A synonym for underlying tables. Each base table in a database is identified by a name unique to the database. Jet also uses the term base table to refer to a table in the current database in contrast to a linked (attached) table. See Linked table.

Batch – A group of statements processed as an entity. Execution of DOS batch files, such as AUTOEXEC.BAT, and SQL statements are examples of a batch process.

Binary file – A file whose content does not consist of lines of text. Executable (.exe), dynamic link library (.dll), and most database files are stored in binary format.

Binary string – A string consisting of binary, not text, data that contains bytes outside the range of ANSI or ASCII values for printable characters. 32-bit Visual Basic 4.0 requires that you store binary strings as arrays of the Byte data type to avoid problems with Unicode/ANSI conversion.

Binding – In database applications, attaching a Data control to a database or a control object to a field of a table or the column of a query result set so that the Data control determines the current record of the table or that the control object reflects the value of the data cell or field of the current record or row. In OLE terminology, binding is the act of connecting an OLE server object to an OLE client. Early binding occurs when you create a reference to an OLE type library. Late binding results from use of the CreateObject or GetObject methods without a type library reference.

Bit – The smallest piece of information processed by a computer. A bit, derived from the contraction of BInary digiT (or Binary digIT) has two states, on (1) or off (0). Eight bits make up a byte, and 16 bits combined is called a word.

Bitwise – A process that evaluates each bit of a combination, such as a byte or word, rather than processing the combination as a single element. Logical operations and masks use bitwise procedures.

Bitmap – The representation of a screen or printed image, usually graphic, as a series of bytes.

Blitting – The process of using the BitBlt() function of Windows' Gdi32.exe to modify a bitmap using bit block transfer.

Boolean – A type of arithmetic in which all digits are bits; that is, the numbers may have only two states, on (true or 1) or off (false or 0). Widely used in set theory and computer programming, Boolean, named after the mathematician George Boole, also is used to describe a VBA data type that may only have two states, true or false. In VBA, True is represented by &HFF (all bits of an 8-bit byte set to 1) and False by &H0 (all bits set to 0).

Bound – See Binding and Object frame.

Break – To cause an interruption in program operation. Ctrl+C is the standard DOS break-key combination but seldom halts operation of a Windows application. Esc is more commonly used in Windows to cause an operation to terminate prior to completion.

Breakpoint – A designated statement that causes program execution to halt after executing the statement preceding it. Breakpoints may be toggled on or off by the F9 function key.

Briefcase replication – A feature of Jet 3.0 running under Windows 95 or Windows NT that permits the creation of Jet replication sets stored in Windows 95 Briefcase folders that can be updated by mobile users. Subsequently, the briefcase replicates are used to update the design-master replica to synchronize the design-master replica with the contents of the briefcase replicas. See Design-master replica.

Buffer – An area in memory of a designated size (number of bytes or characters) reserved, typically, to hold a portion of a file or the value of a variable. When string variables are passed as arguments of DLL functions, you must create a buffer of sufficient size to hold the returned string. This is accomplished by creating a fixed-length string variable of the necessary size, using the String () function, prior to calling the DLL function.

Built-in functions – Functions that are included in a computer language and need not be created by the programmer as user-defined functions.

Business rules – A set of rules for entering data in a database that are specific to an enterprise's methods of conducting its operations. Business rules are in addition to rules for maintaining the domain and referential integrity of tables in a database. Business rules most commonly are implemented in a three-tier client/server database environment. See Three-tier.

Cache – A block of memory reserved for temporary storage. Caches usually store data from disk files in memory to make access to the data faster. By default, Windows 95 caches all disk read and write operations.

Caption – The title that appears in the title bar of a window. Visual Basic calls the text of a label, check box, frame, and command or option button control object the Caption property.

Caret – The term used by Windows to indicate the cursor used when editing a text field, usually shaped as an I-beam. The caret, also called the insertion point, can be positioned independently of the mouse pointer.

Cartesian product – Named for René Descartes, a French mathematician. Used in JOIN operations to describe all possible combinations of rows and columns from each table in a database. The number of rows in a Cartesian product is equal to the number of rows in table 1 times that in table 2 times that in table 3, and so on. Cartesian rows that do not satisfy the JOIN condition are disregarded.

Cascading deletion – A trigger that deletes data from one table based on a deletion from another table to maintain referential integrity. Usually used to delete detail data (for example invoice items) when the master record (invoice) is deleted. Jet 2+ provides cascading deletion as an optional component of its referential integrity features. See Referential integrity.

Case sensitivity – A term used to define whether the interpreter or compiler treats lowercase and uppercase letters as the same character. Most are case-insensitive. C is an exception; it is case sensitive, and all of its keywords are in lower case. Many interpreters, VBA included, reformat keywords to its standard: a combination of uppercase and lowercase letters. VBA does not distinguish between uppercase and lowercase letters used as names for variables. Names of 32-bit Windows API functions are case-sensitive.

Channel – In Windows, channel ordinarily refers to a unique task ID assigned to a dynamic data exchange (DDE) conversation. Channel IDs are Long integers under Windows 95 and Windows NT. Channel is also used to identify an I/O port in mini- and mainframe computers

Check box – A windows dialog and Visual Basic control object that consists of a square box and an associated caption. A diagonal cross or other mark in the box is created or erased (toggled) by alternate clicks on the box or the label with the mouse or by pressing an assigned hot key.

Child – In Windows, usually an abbreviation for an MDI child window. Child is also used in computer programming in general to describe an object that is related to but lower in hierarchical level than a parent object. See also MDI Child.

Chunk – A part of either a RIFF or standard MIDI file that is assigned to a particular function and may be treated as a single element by an application. VBA uses the term chunk to refer to a part of any file that you read or write with the GetChunk and AppendChunk methods. See RIFF.

Class identifier – See CLSID.

Clause – The portion of an SQL statement that begins with a keyword that names a basic operation to be performed.

Client – The device or application that receives data from or manipulates a server device or application. The data may be in the form of a file received from a network file server, an object from an OLE server, or values from a DDE server assigned to client variables. See Automation client.

Clipboard – Windows' temporary storage location for text and graphic objects, as well as Visual Basic objects, such as control objects. The Clipboard is the intermediary in all copy, cut, and paste operations. You can view and save the contents of the Clipboard using the Program Manager's Clipboard applet.

CLSID – An identification tag that is associated with an OLE 2.0 object created by a specific server. CLSID values appear in the Registry and must be unique for each OLE 2.0 server and each type of object that the server can create. See Registry.

Clustered index – An index in which the physical and index order are the same. Equivalent to INDEX ON RECNO() TO . . . in xBase.

Code – Short for source code. The text you enter in your program to create an application. Code consists of instructions and their parameters, functions and their arguments, objects and their events, properties and methods, constants, variable declarations and assignments, and expressions and comments.

Code template – Self-contained groups of modules and resources that perform a group of standard functions and that may be incorporated within other applications requiring these functions, usually with little or no modification.

Code Window – In Visual Basic, the window for editing VBA code contained in forms or modules. Also called the code editing window.

Collection – A group of objects of the same class that are contained within another object. Collections are named as the plural of their object class. As an example, the TableDefs and Fields collections are groups of TableDef and Field objects contained in a Database object.

Color palette – A means of establishing a foreground or background color in Windows by selecting a color from those displayed with the mouse. The color palette then converts the selection to the standard Windows RGB (red/green/blue) color format. The color palette provides the set of colors for graphic objects of 256 colors or less. Also called palette or Windows palette.

COM – An acronym for Component Object Model, the name of Microsoft's design strategy to implement OLE 2+. The final COM implementation will allow networked and cross-platform implementation of OLE 2+ operations and OLE Automation.

Combo box – A Windows object that combines text box and list elements into a single object. In Visual Basic, combo lists are of the drop-down type by default. The list element of a drop-down combo list appears when a downward-pointing arrow to the right of the text box is clicked. Also called a combo list.

Command – A synonym for instruction. Specifies an action to be taken by the computer.

Command button – A Windows object that causes an event when clicked. Command buttons are ordinarily a gray rectangle containing a caption and surrounded by a border.

Comment – Explanatory material within source code not designed to be interpreted or compiled into the final application. In VBA, comments are usually preceded by an apostrophe ('), but can also be created by preceding them with the Rem keyword.

Common Dialog – A standardized dialog box, provided by Windows 95 and Windows NT, that may be created by a Windows API function call to functions contained in Cmdlg32.dll. Common dialogs include FileOpen, FileSave, Print and Printer Setup, ColorPalette, Font, Search and Replace. The Comdlg32.ocx OLE Control lets you implement most of the common dialogs without the necessity of calling Comdlg32.dll functions.

Common User Access – See CUA.

Comparison operators – See Operator.

Compile – To create an executable or object (machine-language) file from source (readable) code. In Visual Basic, compile means to create pseudo-code (tokenized code) from the VBA source code you write in the code editing windows.

Component object model – See COM.

Composite key or index – A key or index based on the values in two or more columns. Equivalent to an INDEX ON field1 + field2 + . . . TO index_filename statement in xBase. See also Key and Index.

Composite menu – A menu that includes menu choices from an OLE 2.0 server application that uses in-place (in-situ) activation (editing). Creating a composite menu also is called grafting a menu.

Composite moniker – The location within a container document or object where the compound document is located.

Compound – In computer programming, a set of instructions or statements that requires more than one keyword or group of related keywords to complete. Select Case. . .Case. . .End Select is an example of a compound statement in VBA.

Compound document – A document that contains OLE objects created by an application other than the application that originally created or is managing the document.

Concatenation – Combining two expressions, usually strings, to form a longer expression. The concatenation operator is & in and SQL, although VBA also permits the + symbol to be used to concatenate strings.

Concurrency – The condition when more than one user has access to a specific set of records or files at the same time. Concurrency is also used to describe the capability of a database management system to handle simultaneous queries against a single set of tables.

Container – An object or application that can create or manipulate compound documents. The OLE 2.0 custom control of is called the OLE container control.

Control – A synonym for a dialog object. Visual Basic's native controls include labels, text boxes, lists, combo lists, option buttons, and command buttons. Visual Basic 4.0 also provides compatibility with 16-bit and 32-bit OLE Controls.

Control array – In Visual Basic, the term given to multiple controls on a single form with the same Name property. Individual controls (elements) of a control array are designated by their index, starting with 0, up to one less than the number of controls with the same name.

Control menu box – See Application Control menu box and Document Control menu box.

Conversation – In DDE operations, the collection of Windows messages that are passed between two different applications, the client and server, during an interprocess communication.

Correlated subquery – A subquery that cannot be independently evaluated. Subqueries depend on an outer query for their result. See also Subquery and Nested query.

Counter – A special field data type of Jet 1.x and 2.0 tables that numbers each new record consecutively, called an AutoNumber field in Jet 3.0. See AutoNumber.

CUA – An abbreviation for Common User Access, an element of IBM's SAA (Systems Application Architecture) specification, which establishes a set of standards for user interaction with menus, dialogs, and other user-interactive portions of an application. The CUA was first implemented in Windows and OS/2 and has been an integral part of these GUIs since their inception.

Current database – The database opened in Access with the Open Database choice of the File menu (or the equivalent) that contains the objects of an Access application. The closest Visual Basic equivalent is the database specified by DBEngine.Workspaces(0).Databases(0) after opening a database.

Current record – The record in a Recordset object whose values you modify. The current record supplies values of the current record's data cells to control objects that are bound to the table's fields.

Current statement – The statement or instruction being executed at a particular instance in time. In debugging or stepwise operation of interpreted applications, it's the next statement that will be executed by the interpreter when program operation is resumed.

Custom control – A control object not native to the application. Visual Basic 3.0 and 16-bit Visual Basic can use 16-bit Visual Basic Extension custom controls (VBXs). Visual Basic 4.0 supports 16-bit VBXs and OCXs, plus 32-bit OCXs. See OLE Control.

Data access object – A synonym for the Jet database engine. The top member of the data access object hierarchy of Jet 2+ is the DBEngine object, which contains Workspace, User, and Group objects in collections. Database objects are contained in Workspace objects.

Data definition – The process of describing databases and database objects such as tables, indexes, views, procedures, rules, default values, triggers, and other characteristics.

Data dictionary – The result of the data definition process. Also used to describe a set of database system tables that contain the data definitions of database objects.

Data element – The value contained in a data cell, also called a data item, or simply an element. A piece of data that describes a single property of a data entity, such as a person's first name, last name, social security number, age, sex, or hair color. In this case, the person is the data entity.

Data entity – A distinguishable set of objects that is the subject of a data table and usually has at least one unique data element. A data entity might be a person (unique social security number), an invoice (unique invoice number), or a vehicle (unique vehicle ID number; license plates are not necessarily unique across state lines).

Data integrity – The maintenance of rules that prevent inadvertent or intentional modifications to the content of a database that would be deleterious to its accuracy or reliability. See Domain integrity and Referential integrity.

Data modification – Changing the content of one or more tables in a database. Data modification includes adding, deleting, or changing information with the INSERT, DELETE, and UPDATE SQL statements. Data modification often is called updating.

Data sharing – The capability to allow more than one user to access information stored in a database from the same or a different application.

Data type – The description of how the computer is to interpret a particular item of data. Fundamental data types are generally divided into two families: strings that usually have text or readable content, and numeric data. The types of numeric data supported varies with the compiler or interpreter used. Most programming languages support a user-defined record or structure data type that can contain multiple data types within it. Field data types, which define the data types of database tables, are distinguished from fundamental data types in this book.

Database – A set of related data tables and other database objects, such as a data dictionary, which are organized as a group.

Database administrator – The individual(s) responsible for the administrative functions of client/server databases. The database administrator (DBA) has privileges (permissions) for all commands that may be executed by the RDBMS and is ordinarily responsible for maintaining system security, including access by users to the RDBMS itself and performing back up and restoration functions.

Database device – A file in which databases and related information, such as transaction logs, are stored. Database devices usually have physical names (for example a DOS or OS/2 file name) and a logical name (the parameter of the USE statement).

Database object – A component of a database. Database objects include tables, views, indexes, procedures, columns, rules, procedures, triggers, and defaults. The DBEngine object of Jet is the topmost member of the class of data access objects.

Database owner – The user who originally created a database. The database owner has control over all of the objects in the database but may delegate control to other users. Jet calls the database owner the Creator. The database owner is identified by the prefix "dbo" in SQL Server.

Date function – A function that provides date and time information or manipulates date and time values.

DDE – An abbreviation for dynamic data exchange, an Interprocess Communication (IPC) method used by Windows and OS/2 to transfer data between different applications.

Deadlock – A condition that occurs when two users with a lock on one data item attempt to lock the other's data item. Most RDBMSs detect this condition, prevent its occurrence, and advise both users of the deadlock situation.

Debug – The act of removing errors in the source code for an application.

Debug Window – A non-modal dialog in which you may enter VBA expressions and view results without writing code in a code editing window. You may also direct information to be displayed in the Debug Window by use of the Debug object. The appearance of the Debug Window varies slightly between VBA-enabled applications.

Declaration – A statement that creates a user-defined data type, names a variable, creates a symbolic constant, or registers the prototypes of functions incorporated within dynamic link libraries.

Declaration section – A section of a VBA module reserved for statements containing declarations.

Declare – In text and not as a keyword, to create a user-defined data type, data holder for a variable, or constant. As a VBA keyword, to register a function contained in a dynamic link library in the declarations section of a module.

Default – A value assigned or an option chosen when no value is specified by the user or assigned by a program statement.

Default database – The logical name of the database assigned to a user when he or she logs in to the database application.

Demand lock – Precludes more shared locks from being set on a data resource. Successive requests for shared locks must wait for the demand lock to be cleared.

Dependent – A condition in which master data in a table (for example, invoices) is associated with detail data in a subsidiary table (invoice items). In this case, invoice items are dependent upon invoices.

Design-master replica – The member of a Jet 3.0 replica set that allows changes in the design of objects, such as tables. The design-master replica usually (but not necessarily) is the .mdb file that is updated by briefcase replicas of the .mdb. See Briefcase replication.

Design mode – One of two modes of operation of Visual Basic, also called design time. Design mode allows you to create and modify forms and control objects, and write VBA code. The other mode is run mode, also called runtime, when the application is executing.

Destination document – A term used by OLE 1.0 to refer to a compound document.

Detail data – Data in a subsidiary table that depends on data in a master table to have meaning or intrinsic value. If one deletes the master invoice records, the subsidiary table's detail data for items included in the invoice lose their reference in the database-they become "orphan data."

Detail table – A table that depends on a master table. Detail tables usually have a many-to-one relationship with the master table. See also Detail data.

Device – A computer system component that is capable of sending or receiving data, such as a keyboard, display, printer, disk drive, or modem. Windows uses device drivers to connect applications to devices.

Device context – A Windows term that describes a record (struct) containing a complete definition of all of the variables required to fully describe a window containing a graphic object. These include the dimensions of the graphic area (viewport), drawing tools (pen, brush) in use, fonts, colors, drawing mode, and so on. Windows provides a handle (hDC) for each device context.

Dialog – A pop-up modal child window, also called a dialog box, that requests information from the user. Dialogs include message boxes, input boxes, and user-defined dialogs for applications such as choosing files to open.

DIB – An acronym for device-independent bitmap, a Windows-specific bitmap format designed to display graphic information. DIB files take the extension .dib and uses a format similar to the .bmp format.

Difference – In data tables, data elements that are contained in one table but not in another.

Directory list – An element of a file selection dialog that selectively lists the subfolders of the designated folder of a specified logical drive.

Distributed database – A database, usually of the client/server type, that is located on more than one database server, often at widely separated locations. Synchronization of data contained in distributed databases is most commonly accomplished by the two-phase commit or replication methods. See Replication and Two-phase commit.

DLL – An abbreviation for dynamic link library, a file containing a collection of Windows functions designed to perform a specific class of operations. Most DLLs carry the .dll extension, but some Windows DLLs, such as Gdi32.exe, use the .exe extension. Functions within DLLs are called (invoked) by applications as necessary to perform the desired operation.

Docfile – The file format for creating persistent OLE objects. Docfiles usually have the extension .ole. Applications that are fully OLE 2–compliant create docfiles with specific extensions, such as .doc (Word) and .xls (Excel). Jet 3.0 .mdb files also are OLE 2 docfiles. OLE 2.1 requires that docfiles include file property values derived from a Properties choice of the File menu.

Document – A programming object that contains information that originates with the user of the application, rather than created by the application itself. The data for documents usually is stored in disk files. Jet tables, Visual Basic and Access forms, and Access reports are documents, as are Excel or Lotus 1-2-3 worksheets. In Windows 95, a document is a file with an association to an application that can display or manipulate the file.

Document Control menu box – The small, square button at the upper left of the menu bar of an application that uses the multiple document interface (MDI). Clicking the Document Control menu box displays the Document Control menu. Double-clicking the Document Control menu box closes the document (but not the application). See also MDI.

Domain – A group of workstations and servers that share a common security account manager (SAM) database and that allow a user to log on to any resource in the domain with a single user ID and password.

Domain integrity – The process of ensuring that values added to fields of a table comply with a set of rules for reasonableness and other constraints. As an example, domain integrity is violated if you enter a ship date value that is earlier than an order data. In Jet databases, domain integrity is maintained by field-level and table-level validation rules. See Business rules.

Drag-and-drop – A Windows process whereby an icon representing an object, such as a file, can be moved (dragged) by the mouse to another location (such as a different directory) and placed (dropped) in it. A specific set of drag-and-drop features is required for Visual Basic applications to qualify for Microsoft's "Designed for Windows 95" logo.

Drive – The logical identifier of a disk drive, usually specified as a letter. When used as a component of a path, the drive letter must be followed by a colon and backslash, as in C:\.

Dynamic data exchange – See DDE.

Dynamic link library – See DLL.

Dynaset – A set of rows and columns in your computer's memory that represent the values in an attached table, a table with a filter applied, or a query result set. You can update the values of the fields of the underlying table(s) by changing the values of the data cells of an updatable Dynaset object. In Jet 2+ Dynaset is a type of Recordset object.

Embedded object – A source document stored as an OLE object in a compound or container document.

Empty – A condition of a VBA variable that has been declared but has not been assigned a value. Empty is not the same as the Null value nor is it equal to the empty or zero-length string ("").

Enabled – The capability of a control object to respond to user actions such as a mouse click, expressed as the True or False value of the Enabled property of the control.

Environment – A combination of the computer hardware, operating system, and user interface. A complete statement of an environment follows: a 486DX2-66 computer with a VGA display and two-button mouse, using the Windows 95 operating system.

Environmental variable – A DOS term for variables that are declared by PATH and SET statements, usually made in an AUTOEXEC.BAT file, and stored in a reserved memory location by DOS. In Windows 95 and Windows NT, required environmental variables are stored in the Registry, although Windows 95 accepts environmental variables in the Autoexec.bat file for backward compatibility with 16-bit Windows applications. The environmental variables may be used by applications to adjust their operation for compatibility with user-specific hardware elements or folder structures.

Equi-join – A JOIN where the values in the columns being joined are compared for equality and all columns in both tables are displayed. This results in two identical columns in the result.

Error trapping – A procedure by which errors generated during the execution of an application are re-routed to a designated group of lines of code (called an error handler) that performs a predefined operation, such as ignoring the error. If errors are not trapped in VBA, the standard modal message dialog with the text message for the error that occurred appears.

Event – The occurrence of an action taken by the user and recognized by one of Visual Basic's events, such as Click or DblClick. Events are usually related to mouse movements and keyboard actions; however, events also can be generated by code using the Timer control, for example.

Event-driven – The property of an operating system or environment, such as Windows, that implies the existence of an idle loop. When an event occurs, the idle loop is exited and event-handler code, specific to the event, is executed. After the event handler has completed its operation, execution returns to the idle loop, awaiting the next event.

Exclusive lock – A lock that prevents others from locking data items until the exclusive lock is cleared. Exclusive locks are placed on data items by update operations, such as SQL's INSERT, UPDATE, and DELETE.

Executable – Code, usually in the form of a disk file, that can be run by the operating system in use to perform a particular set of functions. Executable files in Windows carry the extension .exe and may obtain assistance from dynamic link libraries (DLLs) in performing their tasks.

Exponent – The second element of a number expressed in scientific notation, the power of 10 by which the first element, the mantissa, is multiplied to obtain the actual number. For +1.23E3, the exponent is 3, so you multiply 1.23 by 1,000 (10 to the third power) to obtain the result, 1,230.

Expression – A combination of variable names, values, functions, and operators that return a result, usually assigned to a variable name. Result = 1 + 1 is an expression that returns 2 to the variable named Result. DiffVar = LargeVar - SmallVar returns the difference between the two variables to DiffVar. Functions may be used in expressions, and the expression may return the value determined by the function to the same variable as that of the argument. strVar = Mid$(strVar, 2, 3) replaces the value of strVar with three of its characters, starting at the second character.

Family – In typography, one or more typefaces having a related appearance. Courier roman (standard), italic, and bold constitute the Courier family.

Field – Synonym for a column that contains attribute values. Also, a single item of information in a record or row. In this book, field refers to a column of a table; column is used when referring to query result sets.

Fifth normal form – The rule for relational databases that requires that a table that has been divided into multiple tables must be capable of being reconstructed to its exact original structure by one or more JOIN statements.

File – The logical equivalent of a table. In dBASE, for instance, each table is a single .dbf file.

File moniker – The location of the well-formed path to a persistent OLE 2.0 object.

First normal form – The rule for relational databases that dictates that tables must be flat. Flat tables can contain only one data value set per row. Members of the data value set are called data cells, are contained in one column of the row, and must have only one value.

Flag – A variable, usually Boolean (True/False), that is used to determine the status of a particular condition within an application. The term set is often used to indicate turning a flag from False to True, and reset for the reverse.

Flow control – In general usage, conditional expressions that control the sequence of execution of instructions or statements in the source code of an application. If. . .Then. . .End If is a flow control statement. The term is also used to describe diagrams that describe the mode of operation of an application.

Focus – A Windows term indicating the currently selected application, or one of its windows, to which all user-generated input (keyboard and mouse operations) is directed. The title bar of a window with the focus is colored blue for the default Windows color scheme.

Font – A typeface in a single size, usually expressed in points, of a single style or having a common set of attributes. Font often is misused to indicate a typeface family or style.

Foreground – In multitasking operations, the application or procedure that is visible on-screen and to which user-generated input is directed. In Windows, the application that has the focus is in the foreground.

Foreign key – A column or combination of columns whose value must match a primary key in another table when joined with it. Foreign keys need not be unique for each record or row. See also Primary key.

Form – The fundamental visible element of a Visual Basic application. A Form object contains the control objects that appear on its surface and the code associated with the events, methods, and properties applicable to the form and its control objects.

Form-level – Variables that are declared in the Declarations section of a Visual Basic form. These variables are said to have form-level scope, and are not visible to procedures outside the Form object in which the variables are declared.

Fourth normal form – The rule for relational databases that requires that only related data entities be included in a single table and that tables may not contain data related to more than one data entity when many-to-one relationships exist among the entities.

Frame – In Windows, an enclosure, usually with a single-pixel-wide border, that encloses a group of objects, usually of the dialog class. When referring to SMPTE timing with MIDI files, it is one image of a motion picture film (1/24 second) or one complete occurrence of a television image (approximately 1/30 second in NTSC, 1/25 second in PAL).

Front-end – When used in conjunction with database management systems, an application, a window, or a set of windows by which the user may access and view database records, as well as add to or edit them.

Full server – An OLE 2–compliant executable application capable of providing embeddable or linked documents for insertion into OLE 2 container documents. Excel 7.0, Word 7.0, Project 4.1, and Wordpad are examples of OLE 2.1 full server applications. Access 95 is not a full server, because you cannot embed or link a Jet .mdb file in an OLE 2.1 container application.

Function – A subprogram called from within an expression in which a value is computed and returned to the program that called it through its name. Functions are classified as internal to the application language when their names are keywords. You may create your own, user-defined functions in by adding code between Function FunctionName. . .End Function statements.

Global – Pertaining to the program as a whole. Global variables and constants are accessible to, and global variables may be modified by, code at the form, module, and procedure level. VBA uses the reserved word Public to create or refer to global variables.

Global module – A code module (container) in which all global variables and constants are declared and in which the prototypes of any external functions contained in DLLs are declared. Use of a global module in Visual Basic applications is common but is not required.

Grid – A preset group of visible or imaginary vertical and horizontal lines used to assist in aligning the position of graphic objects. In Visual Basic, the intersection of the imaginary lines is shown as dots on forms in design mode. Control objects automatically align their outlines to these dots if the snap-to-grid option is enabled. In Grid and DBGrid controls, a set of lines that establish the demarcation of columns and rows.

Group – One or more records that are collected into a single category by the SQL GROUP BY clause, usually for the purpose of totaling. Database security systems use the term group to identify a collection of database users with common permissions. See also Permissions.

Handle – An unsigned Long integer assigned by Windows 95 and Windows NT to uniquely identify an instance (occurrence) of a module (application, hModule), task (hTask), window (hWnd), or device context (hDC) of a graphic object. Handles in 32-bit Windows applications, including applications for Windows 95 and Windows NT, are 32-bit unsigned integers (dw or double-words). Also used to identify the sizing elements of control object in design mode. See also Sizing handle.

Header file – A file type used by C and C++ programs to assign data types and names to variables and to declare prototypes of the functions used in the application. C header files usually carry the extension .H.

Hierarchical menu – A menu with multiple levels, consisting of a main menu bar that leads to one or more levels of submenus from which choices of actions are made. Almost all Windows applications use hierarchical menu structures.

Hot-link – A term used to describe a DDE (dynamic data exchange) operation in which a change in the source of the DDE data (the server) is immediately reflected in the object of the destination application (the client) to which has requested it.

Icon – A 32 by 32 pixel graphic image used to identify the application in the program manager window, when the application is minimized, and in other locations in the application chosen by the programmer (such as the Help About dialog). Windows 95 also uses 16 by 16 pixel icons to identify the application in the title bar.

Identifier – A synonym for "name" or "symbol," usually applied to variable and constant names.

Idle – In Windows, the condition or state in which both Windows and the application has processed all pending messages in the queue from user- or hardware-initiated events and is waiting for the next to occur. The idle state is entered in VBA when the interpreter reaches the End Sub statement of the outermost nesting level of procedures for a form or control object. The DBEngine.Idle method suspends processing.

Immediate Window – Replaced in Visual Basic 4.0 and other VBA-enabled applications by the Debug Window. See Debug Window.

In-place activation – The ability to activate an object (launch another application) and have the container application take on the capabilities of the other application. The primary feature of in-place activation (also called in-situ activation) is that the other application's menu choices merge with or replace the container application's menu choices in the active window.

In-process – A term applied to (OLE) Automation servers, also called OLE DLLs, that operate within the same process space (memory allocation) of the OLE Automation client using the server. In-process servers commonly are called InProc servers. See Out-of-process.

Index – For arrays, the position of the particular element with respect to others, usually beginning with 0 as the first element. When used in conjunction with database files or tables, index refers to a lookup table, usually in the form of a file or component of a file, that relates the value of a field in the indexed file to its record or page number and location in the page (if pages are used.)

Infinite loop – A Do While. . .Loop, For. . .Next, or similar program flow control structure in which the condition to exit the loop and continue with succeeding statements is never fulfilled. In For. . .Next loops, infinite looping occurs when the loop counter is set to a value less than that assigned to the To embedded keyword within the structure.

Initialize – In programming, setting all variables to their default values and resetting the point of execution to the first executable line of code. Initialization is accomplished automatically in VBA when you start an application.

Inner query – Synonym for subquery.

Insertion point – The position of the cursor within a block of text. When the cursor is in a text field, it is called the caret in Windows.

Instance – A term used by Windows to describe the temporal existence of a loaded application or one or more of its windows.

Instantiate – The process of creating an instance of an object in memory.

Integer – A whole number. In most programming languages, an integer is a data type that occupies two bytes (16 bits). Integers may have signs (as in the VBA Integer data type), taking on values from -32,768 to +32,767, or be unsigned. In the latter case, integers can represent numbers up to 65,535.

Interface – A noun describing a connection between two dissimilar devices or OLE Automation clients and servers. A common phrase is "user interface," meaning the "connection" between the display-keyboard combination and the user. Adapter cards constitute the interface between the PC data bus and peripheral devices such as displays, modems, CD-ROMs, and the like. Drivers act as a software interface between Windows and the adapter cards. A bridge is an interface between two dissimilar networks. OLE Automation uses Iole. . . interfaces for inter-process communication. Use of interface as a verb is jargon.

Intersection – The group of data elements that are included in both tables that participate in a JOIN operation.

Invocation path – The route through which an object or routine is invoked. If the routine is deeply nested, the path may be quite circuitous.

Invoke – To cause execution of a block of code, particularly a procedure or subprocedure. Invoke also is used to indicate application of a method to an object.

Item – The name given to the elements contained in a list or the list component of a combo box.

Join – A basic operation, initiated by the SQL JOIN statement, that links the rows or records of two or more tables by one or more columns in each table. Equivalent to the xBase SET RELATION TO. . . command.

Jump – In programming, execution of code in a sequence that is not the same as the sequence in which the code appears in the source code. In most cases, a jump skips over a number of lines of code, the result of evaluation of a conditional expression. In some cases, a jump causes another subroutine to be executed.

Key or key field – A field that identifies a record by its value. Tables are usually indexed on key fields. For a field to be a key field, each data item in the field must possess an unique value. See also Primary key and Foreign key.

Key value – A value of a key field included in an index.

Keyword – A word that has specific meaning to the interpreter or compiler in use and causes predefined events to occur when encountered in source code. Keywords differ from reserved words because you can use keywords as variable, procedure, or function names. Using keywords for this purpose, however, is not a good programming practice. You cannot use a reserved word as a variable or constant name.

Label – In VBA programming, a name given to a target line in the source code at which execution results upon the prior execution of a GoTo LabelName instruction. A label also is an Visual Basic control object that displays, but cannot update, text values.

LAN – An acronym for local area network. A LAN is a system comprising multiple computers that are physically interconnected through network adapter cards and cabling. LANs allow one computer to share specified resources, such as disk drives, printers, and modems, with other computers on the LAN.

Launch – To start a Windows application.

Leaf level – The lowest level of an index. Indexes are "botmorphic" and derive the names of their elements from the objects found on trees, such as trunks, limbs, and leaves.

Library – A collection of functions, compiled as a group and accessible to applications by calling the function name, together with any required arguments. DLLs are one type of library; those used by compilers to provide built-in functions are another type.

Library database – An Jet database that is attached to another Jet database. Access library databases usually have the extension .mda. In Visual Basic 4.0, you only can attach a system (Jet 1.x and 2.x .MDA file) or workgroup (Jet 3.0 .mdw file) for secure Jet databases.

Linked object – A source document in a compound document that is included by reference to a file that contains the object's data, rather than by embedding the source document in the compound document.

Linked table – A table that is not stored within a Jet database (native or base table), but which you can manipulate as if the table were a native table. Linked tables were called attached tables in Jet 1.x and 2.0.

List – A Windows control object that provides a list of items from which the user may choose with the mouse or the cursor keys.

Livelock – A request for an exclusive lock on a data item that is repeatedly denied because of shared locks imposed by other users.

Local – The scope of a variable declared within a procedure, rather than at the form, module, or global level. Local variables are visible (defined) only within the procedure in which they were declared. VBA uses the prefix Private to define functions, subprocedures, and variable of local scope.

Local area network – See LAN.

Lock – A restriction of access to a table, portion of a table, or data item imposed to maintain data integrity of a database. Locks may be shared, in which case more than one user can access the locked element(s), or exclusive, where the user with the exclusive lock prevents other users from creating simultaneous shared or exclusive locks on the element(s).

Logical – A synonym for Boolean. Logical is a data type that may have true or false values only. Logical is also used to define a class of operators whose result is only True or False. VBA includes a Boolean data type.

Loop – A compound program flow control structure that causes statements contained between the instructions that designate the beginning and end of the structure to be repeatedly executed until a given condition is satisfied, at which point program execution continues at the source code line after the loop termination statement.

LRPC – An acronym for lightweight remote procedure call used for OLE 2+ operations between OLE clients and OLE full servers on a single computer. LRPC requires that both applications involved in the procedure call be resident on the same computer. See RPC.

Machine language – Program code in the form of instructions that have meaning to and can be acted upon by the computer hardware and operating system employed. Object files compiled from source code are in machine language, as are executable files that consist of object files linked with library files.

Macro – A set of one or more instructions, called actions by Access, that respond to events. Macros, which can substitute for VBA code, are used to automate Access applications. There is no Visual Basic equivalent of Access macros.

Mantissa – The first element of a number expressed in scientific notation that is multiplied by the power of 10 given in the exponent to obtain the actual number. For +1.23E3, the exponent is 3, so you multiply the mantissa, 1.23, by 1,000 (10 to the third power) to obtain the result, 1,230.

MAPI – Acronym for the Windows Messaging API created by Microsoft for use with Microsoft Mail, which implements Simple MAPI. Microsoft Exchange Client and Server implements MAPI 1.0 (also called Extended MAPI).

Master database – A database that controls user access to other databases, usually in a client/server system.

Master table – A table containing data on which detail data in another table is dependent. Master tables have a primary key that is matched to a foreign key in a detail table. Master tables often have a one-to-many relationship with detail tables. Master tables sometimes are called base tables.

MDI server – An OLE 2.0 server that supports multiple compound documents within a single running instance of the application.

Memo – An Jet field data type that can store text with a length of up to about 64,000 bytes (Jet 1.x and 2.x) or 1.2GB (Jet 3.0). (The length of the Text field data type is limited to 255 bytes.)

Menu – A set of choices from which the user determines the next set action to take. The design of menus in Windows is governed by the CUA or Common User Access specification developed by IBM.

Metafile – A type of graphics file, used by Windows and other applications, that stores the objects displayed in the form of mathematical descriptions of lines and surfaces. Windows metafiles, which use the extension .wmf, are a special form of metafiles.

Method – One of the characteristics of an object and a classification of keywords in VBA. Methods are the procedures that are applicable to an object. Methods that are applicable to a class of objects are inherited by other objects of the same class and may be modified to suit the requirements of the object by a characteristic of an object called polymorphism.

Mini-server – An applet with OLE server capabilities that you cannot run as a stand-alone application.

Mission-critical – A cliché used in software and hardware advertising to describe the necessity of use of the promoted product if one wishes to create a reliable database system.

Modal – A dialog that must be closed before further action can be taken by the user.

Modeless – A window or dialog that may be closed or minimized by the user without taking any other action—the opposite of modal.

Module – A block of code, consisting of one or more procedures, for which the source code is stored in a single location (a Form or Module object in Visual Basic). In a compiled language, a code module is compiled to a single object file.

Module level – Variables and constants that are declared in the Declarations section of a module. These variables have module-level scope and are visible (defined) to all procedures that are contained within the module, unless declared Public, in which case the variables are visible to all procedures.

Moniker – A handle to the source of a compound document object.

Monitor – A name often used in place of the more proper terms, display or video display unit (VDU).

Multiprocessing – The ability of a computer with two or more CPUs to allocate tasks (threads) to a specific CPU. Symmetrical multitasking (SMP), implemented in Windows NT, distributes tasks among CPUs using a load-sharing methodology. Applications must be multithreaded to take advantage of SMP.

Multitasking – The capability of a computer with a single CPU to simulate the processing of more than one task at a time. Multitasking is effective when one or more of the applications spends most of its time in an idle state waiting for a user-initiated event such as a keystroke or mouse click.

Multithreaded – An application that contains more than one thread of execution, a task or set of tasks that executes semi-independently of other task(s). The Jet 3.0 database engine is multithreaded (three threads); Visual Basic itself is single-threaded.

Multiuser – Concurrent use of a single computer by more than one user, usually through the use of remote terminals. UNIX is inherently a multiuser operating system. Visual Basic uses the term multiuser to refer to applications involving Jet that share a common .mdb file on a network file server.

Natural join – A SQL JOIN operation in which the values of the columns engaged in the join are compared, with all columns of each table in the join that do not duplicate other columns being included in the result. Same as an equi-join except that the joined columns are not duplicated in the result.

Nested – An expression applied to procedures that call other procedures within an application. The called procedures are said to be nested within the calling procedure. When many calls to subprocedures and sub-subprocedures are made, the last one in the sequence is said to be deeply nested.

Nested object – An OLE 2+ compound document incorporated in another OLE 2+ compound document. You can nest OLE 2+ documents as deeply as you wish. OLE 1.0 does not supported nested objects.

Nested query – An SQL SELECT statement that contains subqueries. See Subquery.

Newline pair – A combination of a carriage return, the Enter key (CR or Chr$(13)), and line feed (LF or Chr$(10)) used to terminate a line of text on-screen or within a text file. Other characters or combinations may be substituted for the CR/LF pair to indicate the type of newline character (soft, hard, deletable, and so on.).

NFS – An abbreviation for Network File Server, a file format and set of drivers created by Sun Microsystems Incorporated, that allows DOS/Windows and UNIX applications to share a single server disk drive running under UNIX.

Non-clustered index – An index that stores key values and pointers to data based on these values. In this case, the leaf level points to data pages rather than to the data itself, as is the case for a clustered index. Equivalent to SET INDEX TO field_name in xBase.

Normal forms – A set of five rules, the first three of which originally were defined by Dr. E. F. Cobb, that are used to design relational databases. Five normal forms are generally accepted in the creation of relational databases. See also First normal form, Second normal form, and so on.

Normalization – Creation of a database according to the five generally accepted rules of normal forms. See also Normal forms.

Not-equal join – A JOIN statement that specifies that the columns engaged in the join do not equal one another. In Jet SQL, you must specify a not-equal join using the SQL WHERE field1 <> field2 clause.

NT – An abbreviation for New Technology used by Windows NT.

NTFS – An abbreviation for New Technology File System, Windows NT's replacement for the DOS FAT (file allocation table) and OS/2's HPFS (high-performance file system). NTFS offers many advantages over other file systems, including improved security and the ability to reconstruct files in the event of hardware failures. Windows 3.1+ and Windows 95 can access files stored on NTFS volumes via a network connection, but cannot open NTFS files directly.

Null – A variable of no value or of unknown value. The default values, 0 for numeric variables and an empty string ("") for string variables, are not the same as the Null value. The NULL value in SQL statements specifies a data cell with no value assigned to the cell.

Object – In programming, elements that combine data (properties) and behavior (methods) in a single container of code called an object. TableDef and QueryDef objects are members of the class of Jet Database objects; a particular control object is a subclass of the control objects class. Objects inherit their properties and methods from the classes above them in the hierarchy and can modify the properties and methods to suit their own purposes. The code container may be part of the language itself, or you may define your own objects in source code.

Object code – Code in machine-readable form that can be executed by your computer's CPU and operating system, usually linked with libraries to create an executable file.

Object frame – A control object that contains and displays or plays an OLE object. Bound OLE container controls display or play OLE objects contained in OLE Object (LongBinary) fields of Jet tables. Unbound OLE container controls display or play objects that are embedded in a Form object or are linked to a file that supplies the object's data. A Visual Basic form (without an OLE container control) can act as a container for an embeddable object, which provides its own object frame.

Object library – A file with the extension .olb that contains information on the objects, properties, and methods exposed by an .exe or .dll file of the same file name that supports OLE Automation.

Object permissions – Permissions granted by the database administrator for others to view and modify the values of database objects, including data in tables. See also Statement permissions.

ODBC – An abbreviation for the Microsoft Open Database Connectivity API, a set of functions that provide access to client/server RDBMSs, desktop database files, text files, and Excel worksheet files through ODBC drivers. Jet 3.0 uses 32-bit ODBC 2.5 and requires 32-bit ODBC drivers. ODBC most commonly is used to connect to client/server databases, such as Microsoft SQL Server, Sybase SQL Server and System 10+, Informix, and Oracle7. Jet 3.0 includes a 32-bit ODBC 2.5 driver for Microsoft SQL Server 4.2+.

Offset – The number of bytes from a reference point, usually the beginning of a file, to the particular byte of interest. The first byte in a file, when offset is used for location, is always 0.

OLE Automation – An extension of OLE 2+ that provides the framework (interfaces) for applications and libraries to expose programmable objects that can be manipulated by client applications. Applications that expose programmable objects are called (OLE) Automation servers. When this edition was written only VBA-enabled applications, plus Access 2.0 and Visual Basic 3.0, were capable of manipulating programmable objects. See Programmable object.

OLE Control – An in-process OLE Automation server with the extension .ocx that exposes a single object, plus the properties, methods, and events of the object. Exposing events differentiates OLE Controls from other types of (OLE) Automation servers. Visual Basic and Access refer to OLE Controls (the official Microsoft term) as Custom Controls; the term Custom Control is more commonly used for 16-bit Visual Basic Extensions, VBXs.

OLE DLL – A synonym for an in-process OLE Automation server implemented as a Windows DLL. See In-process.

OpenDoc – A standard proposed by Apple Computer, Borland International, Lotus Development, Novell, and other competitors of Microsoft to supplant or replace OLE 2+.

Operand – One of the variables or constants upon which an operator acts. In 1 + 2 = 3, both 1 and 2 are operands; + and = are the operators. See Operator.

Operating system – Applications that translate basic instructions, such as keyboard input, to language understood by the computer. The most common operating systems used with personal computers are MS-DOS (Microsoft Disk Operating System), Windows 95, Windows NT, UNIX, and OS/2.

Operator – A keyword or reserved symbol that, in its unary form, acts on a single variable, otherwise on two variables, to give a result. Operators may be of the conventional mathematic type such as +, - (subtract), /, and * (multiply), as well as logical, such as And or Not. The unary minus (-), when applied to a single variable in a statement such as intVar = - intVar inverts the sign of intVar from - to + or from + to -.

Optimistic locking – A method of locking a record or page of a table that makes the assumption that the probability of other users locking the same record or page is low. With optimistic locking, the record or page is locked only when the data is updated, not during the editing process (LockEdits property set to False).

Option button – A synonym for radio button, the original terminology in the CUA specification. Option buttons are circular control objects whose center is filled when selected. If grouped, only one option button of a group may be selected.

Outer join – An SQL JOIN operation in which all rows of the joined tables are returned, whether or not a match is made between columns. SQL database managers that do not support the OUTER JOIN reserved words use the *= (LEFT JOIN) operator to specify that all of the rows in the preceding table return and =* (RIGHT JOIN) to return all of the rows in the succeeding table.

Outer query – A synonym for the primary query in a statement that includes a subquery. See also Subquery.

Out-of-process – An (OLE) Automation server in the form of an executable (.exe) file that operates in its own process space (memory allocation) and uses LRPCs (lightweight remote procedure calls) to communicate with the Automation client. The term OutOfProc often is used as shorthand for out-of-process.

Page – In tables of client/server RDBMSs, such as Microsoft SQL Server, and Jet databases, a 2KB block that contains records of tables. Most client/server and Jet databases lock pages, while DOS desktop databases usually lock individual records. Page-locking is required by most RDBMSs when variable-length records are used in tables. (Oracle 7+ RDBMSs have record-locking capability.)

Parameter – The equivalent of an argument but associated with the procedure that receives the value of an argument from the calling function. The terms parameter and argument, however, are often used interchangeably.

Parse – The process of determining if a particular expression is contained within another expression. Parsing breaks program statements into keywords, operators, operands, arguments, and parameters for subsequent processing of each by the computer. Parsing string variables involves searching for the occurrence of a particular character or set of characters in the string and then taking a specified set of actions when found or not found.

Permissions – Authority given by the system administrator, database administrator, or database owner to perform operations on a network or upon data objects in a database.

Persistent (graphics) – A Windows graphic image that survives movement, resizing, or overwriting of the window in which it appears. Persistent images are stored in global memory blocks and are not released until the window containing them is destroyed.

Persistent (objects) – An object that is stored in the form of a file or an element of a file, rather than only in memory. Jet TableDef and QueryDef objects are persistent because these objects are stored in .mdb files. Recordset objects, on the other hand, are stored in memory. Such objects are called temporal or impersistent objects.

Pessimistic locking – A method of locking a record or page of a table that makes the assumption that the probability of other users locking the same record or page is high. With pessimistic locking, the record or page is locked during the editing and updating process (LockEdits property set to True).

Point – In typography, the unit of measurement of the vertical dimension of a font, about 1/72 of an inch. The point is also a unit of measurement in Windows, where it represents exactly 1/72 of a logical inch or 20 twips. Unless otherwise specified, all distance measurements in VBA are in twips.

Pointer – A data type that comprises a number representing a memory location. Near pointers are constrained to the 64KB default local data segment. Far pointers can access any location in the computer's memory. Pointers are used extensively in C-language applications to access elements of arrays, strings, structures, and the like. VBA has only one pointer data type-to a zero-terminated string when the ByVal. . .As String keywords are applied to an VBA string passed to an external function contained in a dynamic link library.

Poke – In DDE terminology, the transmission of an unrequested data item to a DDE server by the DDE client. In BASIC language terminology, placing a byte of data in a specific memory location. VBA does not support the BASIC POKE keyword and uses the DDEPoke method for DDE operations.

Precedence – The sequence of execution of operators in statements that contain more than one operator.

Primary key – The column or columns whose individual or combined values (in the case of a composite primary key) uniquely identify a row in a table.

Primary verb – The default verb for activating an OLE 2+ object. Edit is the default verb for most OLE objects except multimedia objects, whose default verb is usually Play.

Print zone – The area of a sheet of paper upon which a printer can create an image. For most laser printers and standard dot-matrix printers, this is 8 inches in width. The vertical dimension is unlimited for dot-matrix printers and usually is 13.5 inches for a laser printer with legal-size paper capabilities.

Printer object – A VBA object representing the printer chosen as the default by the Control Panel Printers function's Set Default choice.

Procedure – A self-contained collection of source code statements, executable as an entity. All VBA procedures begin either with the reserved word Sub or Function, which may be preceded by the Public, Private, or Static reserved words, and terminate with End Sub or End Function.

Process server – An "unofficial" term used in this book to specify an (OLE) Automation server, either in-process or out-of-process, that does not provide user-interface components, such as dialogs or windows. Process servers often are used in three-tier client/server applications to implement business rules. See Business rules and Three-tier.

Program – All of the code required to create an application, consisting basically of declarations, statements, and in Windows, resource definition and help files.

Programmable object – An object exposed by an (OLE) Automation server, together with a set of properties and methods applicable to the object. The exposed object can be manipulated by the application programming language of an (OLE) Automation client application.

Projection – A projection identifies the desired subset of the columns contained in a table. You create a projection with a query that defines the fields of the table you want to display but without criteria that limit the records that are displayed.

Properties window – A window that displays the names and properties of Visual Basic Form and Control objects.

Property – One of the two principal characteristics of objects (the other is methods). Properties define the manifestation of the object, for example, its appearance. Properties may be defined for an object or for the class of objects to which the particular object belongs, in which case they are said to be inherited.

Pseudo-object – Objects that are contained within other OLE 2+ objects, such as the cells of a spreadsheet object.

Qualification – A search condition that data values must meet to be included in the result of the search.

Qualified – To precede the name of a database object with the name of the database and the object's owner or to precede the name of a file with its drive designator and the path to the directory in which the file is stored. The terms well-qualified path and well-formed path to a file appear often in documentation.

Query – A request to retrieve data from a database with the SQL SELECT instruction or to manipulate data in the database, called an "action query" by Jet.

QueryDef – A persistent Jet database object that stores the Jet SQL statements that comprise a query. QueryDef objects are optimized, when applicable, by the Jet database engine's query optimizer and stored in a special optimized format.

RDBMS – An abbreviation for relational database management system. An RDBMS is an application that is capable of creating, organizing, and editing databases; displaying data through user-selected views; and printing formatted reports. Most RDBMSs include at least a macro or macro language, and most provide a system programming language. Access, dBASE, Paradox, and FoxPro are examples of desktop RDBMSs.

Record – A synonym for a user-defined data type, called a structure in C and C++. Record also is used in database applications to define a single element of a relational database file that contains each of the fields defined for the file. Records need not contain data to exist—the xBase command, APPEND BLANK, adds a record to a database that contains default data for strings (all spaces), numeric and date fields (zeroes) but Null data (?) for logical fields. A record is the logical equivalent of the row of a table. A set of related fields or columns of information that are treated as a unit by an RDBMS application.

Recursion – A condition in which a procedure or function calls itself. As a general rule, you should avoid recursive procedures and functions in VBA unless you are an experienced programmer.

Reference – In VBA, the incorporation of pointers to specific sets of programmable objects exposed by Automation servers and manipulated by VBA code in the Automation client. You create a VBA reference to a set of objects exposed by an Automation server, such as Microsoft Excel 7, in the References dialog that is accessible from the Tools | References command of Visual Basic 4.0. Once you declare a reference to the set of objects, the VBA pseudo-compiler checks the syntax of your code against the syntax specified for the referenced object. You also can utilize pre-defined intrinsic constants for the referenced objects in your VBA code. Declaring a reference to an object results in early binding of the object. See Binding.

Referential integrity – Rules governing the relationships between primary keys and foreign keys of tables within a relational database that determine data consistency. Referential integrity requires that the values of every foreign key in every table be matched by the value of a primary key in another table. Jet 2+ includes features for maintaining referential integrity, such as cascading updates and cascading deletions.

Refresh – To cause a Data control to re-execute an underlying query so as to reflect changes others in a multiuser environment have made to the records or to reflect a change in the RecordSource property of the Data control.

Registry – A database that contains information required for the operation of Windows 95 and Windows NT, plus applications installed under Windows 95 and Windows NT. The Windows Registry takes the place of Windows 3.1+'s REG.DAT, WIN.INI, and SYSTEM.INI files, plus PROFILE.INI files installed by Windows 3.1 applications. The Registry also includes user information, such as user IDs, encrypted passwords, and permissions. Windows 95 and Windows NT include RegEdit.exe for editing the Registry. OLE 2+ servers add entries to the Registry to specify the location of their .exe files. Automation servers add Registry entries for each of the objects they expose.

Relation – Synonym for a table or a data table in an RDBMS.

Relational database – See RDBMS.

Relational operators – Relational operators consist of operators such as >, <, <>, and = that compare the values of two operands and return true or false depending on the values compared. They are sometimes called comparative operators.

Remote Automation Object – An out-of-process (OLE) Automation server, usually called a RAO, that resides on a server and is accessible to RAO-compliant applications that connect to the server. When this edition was written, only Visual Basic 4.0 was capable of creating RAOs and creating applications to connect to RAOs. NetworkOLE, expected to be included in Windows NT 4.0 (in beta testing when this edition was written), permits other applications to connect to server-stored RAOs.

Remote Data Object – A substitute for the Jet 3.0 Data Access Object that provides a more direct connection to the ODBC API. The 32-bit (only) Remote Data Object (RDO) is included in the Enterprise edition of Visual Basic 4.0. You can reference the RDO in 32-bit Visual Basic 4.0 and Access 95 applications and write VBA code for the RDO to speed queries against client/server databases. RDO also offers additional RDBMS connection management features

Remote procedure call (RPC) – An interprocess communication method that allows an application to run specific parts of the application on more than one computer in a distributed computing environment. Visual Basic 4.0 is capable of creating Remote Automation Objects (RAOs) that use RPCs for communication over a network.

Replication – The process of duplicating database objects (usually tables) in more than one location, including a method of periodically rationalizing (synchronizing) updates to the objects. Database replication is an alternative to the two-phase commit process. Microsoft SQL Server 6+ supports replication of databases across multiple Windows NT servers. Access 95 includes a graphical replication feature designed for mobile users of Jet databases running Windows 95. In Visual Basic, all replication operations must be written in VBA code. See Briefcase replication and Two-phase commit.

Reserved word – Words that comprise the vocabulary of a programming language and that are reserved for specific use by the programming language. You cannot assign a reserved word as the name of a constant, variable, function, or subprocedure. Although the terms reserved word and keyword often are used interchangeably, they do not describe an identical set of words. See also Keyword.

Restriction – A query statement that defines a subset of the rows of a table based on the value of one or more of its columns.

RGB – A method of specifying colors by using numbers to specify the individual intensities of its red, green, and blue components, the colors created by the three "guns" of the CRT of a color display.

RIFF – An acronym for the Windows Resource Interchange File Format used in conjunction with the Multimedia Extensions to Windows. Depending upon their definition, these files may contain MIDI sequence, sample dump or system exclusive data, waveform files, or data to create graphic images. RIFF is the preferred file format, at least by Microsoft Corporation, for multimedia files; however, few applications create RIFF files.

Rollback – A term used in transaction processing that cancels a proposed transaction that modifies one or more tables and undoes changes, if any, made by the transaction prior to a COMMIT or COMMIT TRANSACTION SQL statement.

Routine – A synonym for procedure.

Row – A set of related columns that describes a specific data entity. A synonym for record.

Row aggregation functions – See Aggregate functions.

Rule – A specification that determines the type of data and value of data that may be entered in a column of a table. Rules are classified as validation rules and business rules.

Run mode – The mode of Visual Basic operation when the Visual Basic interpreter is executing your application, either within the development environment or from an executable file. Run mode is called run-time by Microsoft; however, the term runtime normally refers to errors that occur when running the executable version of an application.

Running state – An OLE 2+ object is in the running state when the application that created the object is launched and has control of the object.

Scope – In programming terminology, the extent of visibility (definition) of a variable. VBA has global (Public, visible to all objects and procedures in the application), form/report (visible to all objects and procedures within a single form or report), module (visible to all procedures in a single module file), and local (Private, visible only within the procedure in which declared) scope. The scope of a variable depends upon where it is declared. See also Global, Form-Level, Module-Level, and Local.

Screen object – A VBA object and object class defined as the entire usable area of the video display unit. All visible form and control objects are members of subclasses of the Screen object.

Scroll bar – Vertical and horizontal bars at the right side and bottom, respectively, of a multiline text box that allow the user to scroll the window to expose otherwise hidden text.

SDI server – An OLE 2+ server that supports only a single compound document (Single Document Interface) within an instance of the application. SDI is the preferred design of applications for Windows 95, however, all Microsoft Office 95 productivity applications are multiple-document interface (MDI) applications. Windows 95's Explorer and Exchange client are examples of SDI applications.

Second normal form – The rule for relational databases requiring that columns that are not key fields each be related to the key field. That is, a row may not contain values in data cells that do not pertain to the value of the key field. In an invoice item table, for instance, the columns of each row must pertain solely to the value of the invoice number key field.

Seek – To locate a specific byte, record, or chunk within a disk file. The Seek method of VBA can only be used in conjunction with Recordset objects of the Table type and requires that the table be indexed.

Select list – The list of column names, separated by commas, that specify the columns to be included in the result of a SELECT statement.

Selection – In Windows, one or more objects that have been chosen by clicking the surface of the object with the mouse or otherwise assigning the focus to the object. When used in conjunction with text, selection means the highlighted text that appears in a text box or window. See also Restriction.

Self-join – An SQL JOIN operation used to compare values within the columns of one table. Self-joins join a table with itself, requiring that the table be assigned two different names, one of which must be an alias.

Separator – A reserved symbol used to distinguish one item from another, as exemplified by the use of the exclamation point (!, bang character) in VBA to separate the name of an object class from a specific object of the class, and an object contained within specified object. The period separator (., dot) separates the names of objects and their methods or properties.

Sequential access file – A file in which one record follows another in the sequence applicable to the application. Text files, for the most part, are sequential.

Server – A computer on a LAN that provides services or resources to client computers by sharing its resources. Servers may be dedicated, in which case they share their resources but do not use them themselves except in performing administrative tasks. Servers in client/server databases are ordinarily dedicated to making database resources available to client computers. Servers may also be used to run applications for users; in which case, the server is called an application server. Peer-to-peer or workgroup servers, such as servers created by using Windows 95 and Windows 95 to share disk folders, are another class of server.

Session – In Visual Basic database applications, an instance of the Jet database engine for a single user, represented by the Workspace object. Jet lets you establish multiple sessions which become members of the Workspaces collection. In RDBMS terminology, the period between the time that a user opens a connection to a database and the time that the connection to the database is closed.

Shared application memory – Memory that is allocated between processes involved in an LRPC call. See also LRPC.

Shared lock – A lock created by read-only operations that does not enable the user who creates the shared lock to modify the data. Other users can place shared locks on data so they can read it, but no user may apply an exclusive lock on the data while any shared locks are in effect.

Shortcut key – A key combination that provides access to a menu choice, macro, or other function of the application in lieu of selection with the mouse.

Single-stepping – A debugging process by which the source code is executed one line at a time to allow you to inspect the value of variables, find infinite loops or remove other types of bugs.

Sizing handle – The small black rectangles on the perimeter of Visual Basic control objects that appear on the surface of the form or report in design mode when the object is selected. You drag the handles of the rectangles to shrink or enlarge the size of control objects.

Source code – The readable form of code that you create in a high-level language. Source code is converted to machine-language object code by a compiler or interpreter.

Source document – A term used by OLE 1.0 to refer to a compound object in a container document.

SQL – An acronym, pronounced either as "sequel" or "seekel," for Structured Query Language, a language developed by IBM Corporation for processing data contained in mainframe computer databases. (SEQUEL is the name of a language, similar to SQL, developed by IBM but no longer in use.) SQL has now been institutionalized by the creation of an ANSI standard for the language.

SQL aggregate functions – See Aggregate functions.

Statement – A syntactically acceptable (to the interpreter or compiler of the chosen language) combination of instructions or keywords and symbols, constants, and variables that must appear on a single line or use the line continuation pair (a space followed by an underscore) to use multiple lines.

Statement permissions – Permissions granted by the owner of a database or the database administrator for other users to execute specified SQL statements that act on the database's objects.

Static – When applied to a variable, a variable that retains its last value until another is assigned, even though the procedure in which it is defined has completed execution. All global variables are static. Variables declared as Static are similar to global variables; however, their visibility is limited to their declared scope. Static is also used to distinguish between statically linked (conventional) executable files and those that use DLLs.

Stored procedure – A set of SQL statements (and with those RDBMSs that support them, flow control statements) that are stored under a procedure name so that the statements can be executed as a group by the database server. Some RDBMSs, such as Microsoft and Sybase SQL Server, pre-compile stored procedures so that they execute more rapidly. Jet 3.0's Remote Data Object is optimized for use with stored procedures.

String – A data type used to contain textual material, such as alphabetic characters and punctuation symbols. Numbers may be included in or constitute the value of string variables, but cannot be manipulated by mathematical operators.

Structure – Two or more keywords that are used together to create an instruction, which is usually conditional in nature. In C and C++ programming, a user-defined data type. See also Compound.

Structured Query Language – See SQL.

Stub – A procedure or user-defined function that, in VBA, consists only of Sub SubName. . .End Sub or Function FnName. . .End Function lines with no intervening code. Stubs for subprocedures are created automatically by the VBA interpreter for event-handling code stored in Form objects. Stubs are used to block out the procedures required by the application that can be called by the Main program. The intervening code statements are filled in during the programming process.

Style – In typography, a characteristic or set of attributes of a member of a family of typefaces created by an outline or bit map designed specifically to implement it. Styles include bold, italic, bold-italic, bold-italic-condensed, and so forth. Styles may contain attributes for weight (bold, demi-bold, black), form (italic, roman), and spacing (compressed or extended) in various combinations.

Submenu – A set of choices presented when a main menu choice is made. In Windows, the first-level submenus are similar to drop-down dialogs. Second-level submenus usually appear horizontally at the point of the first submenu choice.

Subform – A form contained within another form. Microsoft Access has a Subform control; Visual Basic does not.

Subprocedure – A procedure called by another procedure other than the main procedure. (WinMain is the main procedure of a Windows application.)

Subquery – A SQL SELECT statement that is included (nested) within another SELECT, INSERT, UPDATE, or DELETE statement, or nested within another subquery.

Syntax – The rules governing the expression of a language. Like English, Spanish, Esperanto, or Swahili, programming languages each have their own syntax. Some languages allow much more latitude (irregular forms) in their syntax. VBA has a relatively rigid syntax, while C provides more flexibility at the expense of complexity.

System administrator – The individual(s) responsible for the administrative functions for all applications on a LAN or users of a UNIX cluster or network, usually including supervision of all databases on servers attached to the LAN. If the system administrator's (SA's) responsibility is limited to databases, the term database administrator (DBA) is ordinarily assigned.

System colors – The 20 standard colors used by Windows for elements of its pre-defined objects such as backgrounds, scroll bars, borders, and title bars. You may change the system colors from the defaults through Control Panel's Color and Desktop functions.

System databases – Databases that control access to databases on a server or across a LAN. Microsoft SQL Server has three system databases: the master database that controls user databases, tempdb that holds temporary tables, and model that is used as the skeleton to create new user databases. Any database that is not a user database is a system database.

System function – Functions that return data about the database rather than from the content of the database.

System object – An object defined by Visual Basic or VBA rather than by the user. Examples of system objects are the Screen and Debug objects.

System table – A data dictionary table that maintains information on users of the database manager and each database under the control by the system. Jet system tables carry the prefix MSys.

Tab order – The order in which the focus is assigned to multiple control objects within a form or dialog with successive depression of the Tab key.

Table – A database object consisting of a group of rows (records) divided into columns (fields) that contain data or Null values. A table is treated as a database device or object.

Text box – A Windows object designed to receive printable characters typed from the keyboard. Visual Basic provides two basic types: single- and multi-line. Entries in single-line text boxes are terminated with an Enter keystroke. Multi-line text boxes accept more than one line of text, either by a self-contained word-wrap feature (if a horizontal scroll bar is not present) or by a Ctrl+Enter key combination.

Text file – A disk file containing characters with values ordinarily ranging from Chr$(1) through Chr$(127) in which lines of text are separated from one another with newline pairs (Chr$(13) & Chr$(10)).

Theta join – A SQL JOIN operation that uses comparison or relational operators in the JOIN statement. See also Operator.

Third normal form – The rule for relational databases that imposes the requirement that a column that is not a key column may not be dependent upon another column that is not a key column. The third normal form is generally considered the most important because it is the first in the series that is not intuitive.

Thread – A part of a process, such as an executing application, that can run as an object or an entity.

Three-tier – The architecture of a database application, usually involving a client/server RDBMS, where the front-end application is separated from the back-end RDBMS by a middle tier application. In Visual Basic applications, the middle tier usually is implemented as an OLE Automation process server, which implements the database connection, enforces business rules, and handles transfer of data to and from databases of the RDBMS. See Business rules and Process server.

Time stamp – The date and time data attributes applied to a disk file when created or edited. Time stamp is a database type for SQL Server and the ODBC API.

Timer – A Visual Basic control object that is invisible in run mode and that is used to trigger a Timer event at preselected intervals.

Title bar – The heading area, usually blue, of a window in which the title of the window appears, usually in bright white (reverse).

Toggle – A property of an object, such as a check box, that alternates its state when repeatedly clicked with the mouse or activated by a shortcut key combination.

Toolbar – A group of command button icons, usually arranged horizontally across the top of a window, that perform functions that would ordinarily require one or more menu choices. Floating toolbars can be located anywhere on your display.

Toolbox – A collection of command buttons designated as tools, usually with icons substituted for the default appearance of a command button, that choose a method applicable to an object (usually graphic) until another tool is selected. An example is the Visual Basic toolbox.

Topic – In DDE conversations, the name of the file or other identifying title of a collection of data. When used in conjunction with help files, the name of the subject matter of a single help screen display.

TRANSACT-SQL – A superset of ANSI SQL used by Microsoft and Sybase SQL Server. TRANSACT-SQL includes flow control instructions and the capability to define and use stored procedures that include conditional execution and looping.

Transaction – A group of processing steps that are treated as a single activity to perform a desired result. A transaction might entail all of the steps necessary to modify the values in or add records to each table involved when a new invoice is created. RDBMSs that are capable of transaction processing usually include the capability to cancel the transaction by a rollback instruction or to cause it to become a permanent part of the tables with the COMMIT or COMMIT TRANSACTION statement. See Rollback.

Trigger – A stored procedure that occurs when a user executes an instruction that may affect the referential integrity of a database. Triggers usually occur prior to the execution of INSERT, DELETE, or UPDATE statements so that the effect of the statement on referential integrity can be examined by a stored procedure prior to execution. See also Stored procedure.

Twip – The smallest unit of measurement in Windows and the default unit of measurement of VBA. The twip is 1/20 of a point, or 1/1440 of a logical inch.

Two-phase commit – A process applicable to updates to multiple (distributed) databases that prevents a transaction from completing until all of the distributed databases acknowledge that the transaction can be completed. The replication process has supplanted two-phase commit in most of today's distributed client/server RDBMSs. See Replication.

Type – See Data type.

Typeface – Synonym for face. A set of fonts of a single family in any available size possessing an identical style or set of attributes.

Type library – A file with the extension .tlb that provides information about the types of objects exposed by an (OLE) Automation server. As an example, the type library for Msaccess.exe is Msaccess.tlb. See Object library.

Unary – See Operator.

UNC – An abbreviation for Unified Naming Convention, the method of identifying the location of files on a remote server. UNC names begin with \\. Windows 95 and Windows NT support UNC; 32-bit Windows applications must support UNC to qualify for application of Microsoft's "Designed for Windows 95" logo. All Microsoft Office 95 applications support UNC.

Unicode – A replacement for the 7-bit or 8-bit ASCII and ANSI representations of characters with a 16-bit model that allows a wider variety of characters to be used. Windows 95 and Windows NT support Unicode. 32-bit Visual Basic automatically converts Unicode to ANSI and vice-versa.

Uniform data transfer (UDT) – The interprocess communication (IPC) method used by OLE 2+. OLE 1.0 uses DDE for IPC.

Unique index – An index in which no two key fields or combinations of key fields upon which the index is created may have the same value.

UNIX – Registered trademark of Novell, Incorporated (formerly of AT&T) for its multiuser operating system, now administered by the Open Systems Foundation (OSF). Extensions and modifications of UNIX include DEC Ultrix, SCO UNIX, IBM AIX, and similar products.

Update – A permanent change to data values in one or more data tables. An update occurs when the INSERT, DELETE, UPDATE, or TRUNCATE TABLE SQL commands are executed.

User-defined – A data type, also called a record, that is specified in your VBA source code by a Type. . .End Type declaration statement in the Declarations Section of a module. The elements of the user-defined record type can be any data type valid for the language and may include other user-defined types.

User-defined transaction – A group of instructions combined under a single name and executed as a block when the name is invoked in a statement executed by the user.

Validation – The process of determining if an update to a value in a table's data cell is within a pre-established range or is a member of a set of allowable values. Validation rules establish the range or set of allowable values. Jet 2+ supports validation rules at the field and table levels.

Variable – The name given to a symbol that represents or substitutes for a number (numeric), letter, or combination of letters (string).

VBA – An abbreviation for Visual Basic for Applications, the official name of which is "Visual Basic, Applications Edition." VBA is Microsoft's common application programming (macro) language for Access 95, Excel 5+, Project 4+, and Visual Basic 4.0. Each application has it's own "flavor" of VBA as a result of automatically-created references to the application's object hierarchy in VBA code. Thus this book uses the terms Access VBA, Excel VBA, and Project VBA when referring to a particular flavor of VBA. VBA is used when the subject matter is applicable to the version of VBA implemented by Visual Basic 4.0.

View – The method by which the data is presented for review by the user, usually on the computer display. Views can be created from subsets of columns from one or more tables by implementing the SQL CREATE VIEW instruction.

Visual Basic for Applications – See VBA.

WAN – An acronym for wide area network. A WAN is a system for connecting multiple computers in different geographical locations through the use of the switched telephone network or leased data lines, by optical or other long-distance cabling, or by infra-red, radio, or satellite links.

WAVE file – A file containing waveform audio data, usually with a .wav extension.

Waveform audio – A data type standard of the Windows Multimedia Extensions that defines how digitally sampled sounds are stored in files and processed by Windows API functions calls.

Wildcard – A character that substitutes for and allows a match by any character or set of characters in its place. The DOS ? and * wildcards are similarly used in Windows applications.

Win32 – An API for creating 32-bit applications that run under Windows 95 and Windows NT. Applications that are written to the Win32 API are purported to provide substantially improved performance when run under Windows 95 and Windows NT.

Win32S – A subset of the Win32 API designed to add limited 32-bit capabilities to Windows 3.1+. Very few applications have been written to the Win32S API, which appears to have become obsolete.

WinHelp32 – A contraction used to describe the Windows help engine of Windows 95 and the files that are used in the creation of Windows 95 help systems. WinHelp32 offers many useful built-in features not available in 16-bit WinHelp, including full-text indexing and search capability.

Workstation – A client computer on a LAN or WAN that is used to run applications and is connected to a server from which it obtains data shared with other computers. It is possible, but not common, for some network servers to be used as both a server and a workstation. Microsoft Windows NT, for instance, permits this. Workstation is also used to describe a high-priced PC that uses a proprietary microprocessor and proprietary architecture to create what some call an "open" system.

WOSA – Acronym for the Windows Open Services Architecture that is the foundation for such APIs as ODBC, MAPI, and TAPI. Microsoft also develops special vertical-market WOSA APIs for the banking, financial, and other industries.

WOW – An acronym for Windows on Win32, a subsystem of Windows NT that allows 16-bit Windows applications to run in protected memory spaces called virtual DOS machines (VDMs).

xBase – Any language interpreter or compiler or a database manager built upon the dBASE III+ model and incorporating all dBASE III+ commands and functions. Microsoft's FoxPro and Computer Associates' Clipper are xBase dialects. Most xBase database managers add a substantial number of commands and functions to the dBASE III+ vocabulary. xBase RDBMSs often do not use the same index file structure as dBASE III+, but all use the same database file (.DBF) structure.

Yes/No field – A term originally used by Access to describe a field of a table whose allowable values are Yes (True) or No (False). Yes/No fields are called a logical or Boolean fields by other RDBMSs.