expression

    An expression whose value controls the number of times the range
    is to be assembled within the program. When the expression is
    less than or equal to 0, the repeat block is not assembled. The
    expression must be absolute or relocatable and must not contain
    any undefined symbols. The assembler converts a relocatable value
    to the relative offset within the psect.

 range

    The source text to be repeated the number of times specified by
    the value of the expression. The repeat block can contain macro
    definitions or other repeat blocks. .MEXIT is legal within the
    range and causes the current and all succeeding repetitions to be
    aborted.