Using Predefined Fields (PDFs)
You can make use of predefined fields in three ways:
You can display and optionally allow a user to modify the value of a predefined field by painting it on an image. For example, you may want to display the value of COMPANY NAME on an input screen for the user's information.
Using statements, you can check the value of any predefined field and, based on the result, control the flow of processing For example, you may want to determine if there were any errors encountered during an output process and, if there were errors, perform a special error-handling routine. You can examine the value of the ERRORS predefined field and, if it is greater than zero, pass control to the error-handling routine.
You can use statements to set the value of certain predefined fields and control how a process operates. For example, you may want to control which alternate image is to appear on the screen by examining a user's response to a preliminary question. Depending on the response, you can set the value of ALTERNATE IMAGE NUMBER to the appropriate value, and cause the proper image to be displayed.
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