The WHILE command causes the execution of the following statement block provided the condition is true. It is equivalent to FOR(;condition;). WHILE commands may be nested.

WHILE(condition)
	statement-block

conditionspecifies the looping condition. When this is false the statement block is skipped.

WHILE(FLAG==0) READ(5) A,FLAG

WHILE (I>0)
$(
CH(J)=IBUF(I)
I=I-1; J=J+1
$)