1  –  beginning-label:

    Assigns a name to the REPEAT statement. A beginning label used
    with the LEAVE statement lets you perform a controlled exit from
    a repeat loop. A named repeat loop is called a labeled repeat
    loop statement. A beginning label must be unique within the
    procedure in which the label is contained.

2  –  END REPEAT ending-label

    Marks the end of a control loop. If you choose to include the
    optional ending label, it must match exactly its corresponding
    beginning label. An ending label must be unique within the
    procedure in which the label is contained.

    The optional ending-label argument makes multistatement
    procedures easier to read, especially in complex multistatement
    procedure blocks.

3  –  REPEAT compound-use-statement

    Repeatedly executes a block of SQL statements until an end
    condition is met, as specified by the UNTIL predicate clause.

4  –  UNTIL predicate

    Specifies a condition that controls how many times SQL can
    execute the statements embedded within its REPEAT . . . UNTIL
    block (collectively referred to as its compound statement). SQL
    executes the compound statement once and then evaluates the UNTIL
    condition. If it evaluates to false or NULL (unknown) and does
    not encounter an error exception, SQL executes the compound
    statement again. Each time the search condition evaluates
    to false or NULL, the REPEAT statement executes the compound
    statement. If the UNTIL condition evaluates to true, SQL bypasses
    the compound statement and passes control to the statement after
    the END REPEAT statement.