This is a unique join key assigned by CCW/CMS to assist the user in joining the base claim to a line claim for each encounter record.
Each IP, SNF, HH or OP Encounter base record has at least one revenue center record.
Each Carrier or DME Encounter base record has at least one line record.
All revenue center records or lines on a given encounter record have the same ENC_JOIN_KEY. It is used to link the revenue lines together and/or to the base claim.