The syntax of a repeat statement is
repeat statement1; ...; statementn; until expression
where expression returns a Boolean value. (The last semicolon before until is optional.) The repeat statement executes its sequence of constituent statements continually, testing expression after each iteration. When expression returns True, the repeat statement terminates. The sequence is always executed at least once because expression is not evaluated until after the first iteration.
Examples of repeat statements include
repeat
K := I mod J;
I := J;
J := K;
until J = 0;
repeat
Write('Enter a value (0..9): ');
Readln(I);
until (I >= 0) and (I <= 9);