The WHILE statement executes the specified statement as long as the condition defined in the expression is met.

[<label> :] WHILE <expression> DO <procedural-statement> END WHILE [<label>]
label
(optional) is the identifier for the WHILE statement that can be referenced by other statements. If specified, the label at the beginning of the statement must match the label at the end.
expression
is the expression that is evaluated to determine whether the condition is met.
procedural_statement
is the procedural statement that is executed when a condition is met.