You use validity checks to automatically verify data input by the user. Code validity checks after any translate lists.

To associate a validity check with a variable class, code the CHECKL (check list) tag and its required end tag either following the last translate list, or if no translate list exists, following the VARCLASS start tag. The individual check item that defines the test to perform is coded using the CHECKI (check item) tag nested within the check list. You can code one CHECKI tag in a CHECKL definition. However, you can code multiple CHECKL tags within a variable class definition.

There is an optional MSG attribute on the CHECKL tag that allows you to specify your own message to display when the entered value fails the test. If you do not specify a message, ISPF Dialog Manager supplies a default message for you. For more information about defining your own messages, see Messages.

A value entered by the user must pass the check item test for the check list to be considered successful. Furthermore, because there can be multiple check lists defined, all check lists must be successful for the validation to be successful.

The TYPE attribute of the CHECKI tag allows you to specify the various validity tests of the input.