WHILE: Repeated execution of a program segment while a specified condition is true. Testing of condition is done prior to the execution of the program segment.

syntax:
:WHILE condition
:command while condition is true
:command while condition is true
:END
:command

WHILE performs a group of commands while condition is true. condition is tested when WHILE is encountered. If condition is true (nonzero), the program executes a group of commands. END signifies the end of the group. If condition is false (zero), the program executes the commands following END. WHILE instructions can be nested.