Field functions are specific to the field in which they are installed. Each field can have its own begin-field and/or end-field function.
The begin-field function is useful for automatically displaying a window with information or a menu when the user enters a field. The begin-field function can be used for performing any desired processing prior to turning over control of a field to the user.
The end-field function is generally more useful than the begin-field function for controlling processing flow. The system calls the end-field function after the data in the field has been validated, and before the user moves into another field. This is a good place for branching to other fields, forms, or menus.
End-field functions are also very useful when you need to use the data just entered in the field. For instance, in an end-field function, you can get the data entered in the field and, based on the value that the user entered, branch to another form or calculate and display a running total in another field on the form.
What You Should Not Do in Begin- and End-Field Functions
Writing and Installing Begin- and End-Field Functions
