Identifies the first circuit or segment as a unique number.
NOTE 1: The REF NUM is customer assigned and is returned on the confirmation record to the ordering customer.
NOTE 2: Once REF NUM is generated it cannot be changed and is retained through completion of the request.
NOTE 3: The values are to be assigned consecutively beginning with "0002" to "N", where "N" is the total number of legs and ACTL to bridge and bridge to bridge segments. The value "0001" is reserved for the "backbone" (the ACTL to bridge segment) which is not entered on the MSL request. For multipoint configurations the REF NUM total will always be "one" greater than the number of legs (NSL plus one) because "0001" is assigned to the ACTL to bridge segment.
NOTE 4: When a specific circuit or segment, identified by its REF NUM, has been canceled in the request provided by the customer, the corresponding REF NUM will not be included in any subsequent versions. The remaining circuit or segments will maintain their original association and not be renumbered.
USAGE: This field is required.
DATA CHARACTERISTICS: 4 numeric characters
EXAMPLE: 0 0 0 2