Coding Each AOF Rule Type › Screen Rules › How Screen Rules Are Triggered

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.