This variable is the unique plan benefit package (PBP) number for the Part D plan sponsor's contract. CMS assigns an identifier to each PBP within a contract that a Part D plan sponsor has with CMS. This field is a key that links of Part D sponsor's contract and plan identifiers.
Prior to 2015, this variable was always encrypted to comply with CMS privacy rules. You need to know both the Part D contract number (variable called CONTRACT_ID) and plan benefit package identifier in order to identify the specific plan benefit package offered to beneficiaries. The CCW constructs the Plan Characteristics File from information submitted by Part D plan sponsors to CMS's Health Plan Management System (HPMS).