The Data Dictionary (Data Elements and Structures)

The Data Dictionary component of APPX allows you to specify information about the data and files that are used in an application. Data dictionary options, shown in Figure 1-1-3 below, are available from the Application Design Specifications Menu under the heading "Data Elements and Structures".

Figure 1-1-3. Data Dictionary Options

The dictionary specifications provide a central location for all data and file attributes that the processes (menus, inputs, outputs, etc.) reference as they are developed. The APPX dictionary is active, or integrated, meaning that all the information a designer specifies in the dictionary is used by, and places restrictions on, all other parts of an application. For example, if you specify in the dictionary that the value of a field called AMOUNT cannot exceed 100, an end user could not enter a value of 105 on any input screen where this field appears. In addition, if you expand the length of a field from seven to eight characters in the dictionary, after the dictionary is processed the field appears as eight characters wherever it is referenced in the application. As a designer, you do not need to make any other modifications to accommodate this change in field length, unless the change would cause fields to overlap on a screen or in a report.

A preliminary discussion of the dictionary can be found in Chapter 1-3: Data Dictionary while Chapters 2-1, 2-2, 2-3, 2-4, and 2-5 define the Data Dictionary in more detail.