IF... ENDIF conditions 

If you want to make, e.g. the execution of functions depend on the contents of a variable, you can set a condition for its execution.

Enter IF in the Funct. column, and the condition (see : Use condition) in the Text column. The Object column remains empty.

IF <condition>
... CATT functions
ENDIF

The CATT functions specified between IF and ENDIF are only performed if the condition is satisfied.

You can nest IF...ENDIF blocks and DO...ENDDO loops.