/UNDEFINE

Use the /UNDEFINE directive to indicate that a condition is no longer defined.

Start of change/UNDEFINE must be followed by at least one space, and then the condition-name must be specified on the same line. The remainder of the line must be blank.End of change

Start of changeSee Compiler Directives for information on the columns available for directives.End of change

Start of change/UNDEFINE cannot be specified within a free-form statement.End of change

The /UNDEFINE directive removes a condition-name from the list of currently defined conditions. A subsequent /IF DEFINED(condtion-name) would be false. A subsequent /IF NOT DEFINED(condition-name) would be true.
Note: Any conditions specified on the DEFINE parameter will be considered to be defined when processing /IF and /ELSEIF directives. These conditions can be removed using the /UNDEFINE directive.