How Screen Rules Are Triggered

The following information concerns how screen rules are triggered:

Screen update events and keyboard unlocking events occur after the host application sends a VTAM Request Unit (RU) chain.
- Some applications (such as ISPF) send a full screen of data using multiple RUs
- Other applications (such as native TSO in READY mode) send one line of data per RU.
A screen rule executes once per screen event. For example, a rule triggered when the word READY appears in a screen update executes only once even if READY appears three times on the screen.
A rule triggered by any change, either to an entire screen or to a portion of a screen, executes only once.
The string contained in the SCR.TEXT event-related variable indicates the first position (row and column) of the change and the new text found at that location.
If your rule is concerned with specific screen updates, have the rule check the SCR.TYPE event-related variable for the SCRUPDATE screen-update value.
Because SCR rules allow multiple spec lines, they must be followed by a section header before comments can be used; either a )INIT card must be inserted prior to the comment card or the comment must be moved after the )PROC card.