Why the recorded descriptions work

The recorded descriptions automatically created by HCL ZIETrans work well for at least three reasons.

First, the OIA descriptor, cursor position, and number of input fields can be applied to every possible application screen. That is, every application screen has some number of input fields (perhaps the number is 0), a starting cursor position, and an input inhibited indicator that is either set or cleared.

Second, the combination of the number of input fields and the cursor position provides a pretty reliable description of an application screen, because application screens typically contain many fields, but only a certain number of them are input fields. The cursor position is always in the first input field.

Third, and perhaps most important, during screen recognition the macro runtime compares the new application screen to a short list (usually a very short list) of macro screens called valid next screens (see Stages in processing a macro screen). Therefore a single macro screen need not be differentiated from every other macro screen in the macro, only from the other screens in the list of valid next screens. Frequently the list consists of a single macro screen.