single-entry PHR MAC CE is identified by a MAC PDU subheader with LCID index 57. It has a fixed size of two octets, including power headroom which indi- cates the PH level (6 bits) and PCMAXIm denoting the maximum permissible UE transmit power for carrier l and serving cell m. The multiple-entry PHR MAC CE is identified by a MAC PDU subheader with LCID index 56. It has a variable size and may include a bitmap, a Type 2 PH field and an octet containing the associated PCMAXIm field for the SpCell of the other MAC entity, as well as a Type 1 PH field and an octet containing the associated PCMAXIm for the primary cell (PCell). It may further include one or more Type X PH fields (x is either 1 or 3) and octets containing the associated PCMAX|m fields for serv- ing cells other than PCell indicated in the bitmap. The MAC entity determines whether power headroom value for an activated serving cell is based on a real trans- mission or a reference format by considering the configured grant(s) and the down- link control information (DCI) that has been received prior to the PDCCH occasion 208 Chapter 2 in which the first uplink grant for a new transmission is received after a PHR has been triggered. Configured grant confirmation The configured grant confirmation MAC CE is identified by a MAC PDU subhea- der with LCID index 55, which has a fixed size of zero bits. C-RNTI The C-RNTI MAC CE is identified by a MAC PDU subheader with LCID index 58. It has a fixed size and consists of a single field containing the C-RNTI. The length of the field is 16 bits. Buffer status report (BSR) The BSR MAC CEs consist of short BSR format (fixed size), long BSR format (variable size), short truncated BSR format (fixed size), and long truncated BSR for- mat (variable size). The BSR formats are identified by MAC PDU subheaders with LCID indices 59, 60, 61, and 62 corresponding to short truncated BSR, long trun- cated BSR, short BSR, and long BSR MAC CEs, respectively. The fields in the BSR MAC CE contain an LCG ID, denoting the LCG ID which ide