IF-THEN-ELSE: Conditional execution of a two-branch program segment.

syntax:
:IF condition
:THEN
:command if true
:command if true
:ELSE
:command if false
:command if false
:END
:command

IF-THEN-ELSE is used for testing and branching for a two-branch program segment. If condition is true (nonzero), then the group of commands in between THEN and ELSE is executed. If condition is false (zero), then the group of commands in between THEN and ELSE is skipped and the group of commands in between ELSE and END is executed. END identifies the end of the two-branch program segment.