Code identifying a loop within the transaction set which is bounded by the related LS and LE segments (corresponding LS and LE segments must have the same value for loop identifier). (Note: The loop ID number given on the transaction set diagram is recommended as the value for this data element in segments LS and LE.)

One loop may be nested (contained) within another loop, provided the inner (nested) loop terminates before the outer loop. When specified by the standard setting body as ``mandatory'', this segment, in combination with ``LS'', must be used. It is not to be used if not specifically set forth for use. The loop identifier in the loop header and trailer must be identical. The preferrd value for the identifier is the segment ID of the required loop beginning segment.