Valid next screens
When a host application has displayed an application screen in the host terminal, and a user input has occurred, then usually only a few application screens (frequently just one) can occur next.
In the example scenario, the current macro screen is Screen1, the
current application screen is the ISPF Primary Option menu, and the
input is '3'
plus the enter key (see Contents
of macro screen Screen1). In this context, only one application
screen can occur next, the Utility Selection Panel. Therefore the
name of only one macro screen needs to be added to the list of valid
next screens: Screen2.
This might seem at first to be counter-intuitive. After all, the ISPF Primary Option Menu has about 30 different possible inputs (15 options, 6 menu selections, and 8 function keys). There should be 30 names of macro screens on the list, not just 1, right?
The reason that the list of valid next screens usually has only
one or a few names on it is that the macro is executing a series of
instructions that are aimed at accomplishing some specific task. In
Screen1, the instructions are aimed at getting from the ISPF Primary
Option Menu to the Utility Selection Panel. The necessary actions
have been performed to make this transition occur ('3[enter]'
),
and the macro screen is now just waiting for the expected application
screen to appear.