on with Content Retention (DCR) mode is enabled, the network assigns a 72-bit CRID to each MS during network entry or on handover to an IEEE 802.16m BS in a mixed-mode operation. The MS is identified by the CRID in coverage loss recovery and DCR mode, where the CRID allows the network to retrieve the MS context. The network may assign the MS a new CRID if necessary. E-MBS Identifier: a 12-bit value that is used along with a 4-bit FID to uniquely identify a specific E-MBS flow in an E-MBS zone. In order to protect the mapping between the STID and the MS MAC address, two types of STIDs are assigned to an MS during network entry: a temporary STID and a permanent STID. A TSTID is assigned during the initial ranging process and is used until the permanent STID is prescribed. The permanent STID is assigned during the registration with the BS and after successful authentication 'The IEEE defined 48-bit extended unique identifier (EUI-48TM) is a concatenation of either a 24-bit Organizationally Unique Identifier (OUI) value administered by the IEEE Registration Authority and a 24-bit extension identifier assigned by the organization with that OUI assignment, or the concatenation of a 36-bit Individual Address Block (IAB) identifier or 36-bit Organizationally Unique Identifier (OUI-36), and a 12-bit extension identifier assigned by the organization with that IAB assignment. The IEEE administers the assignment of 24-bit OUI values and 36-bit OUI-36 or IAB identifiers. The assignments of these values are public, SO that a user of an EUI-48 value can identify the manufacturer that provided the value. See http://standards.ieee.org/regauth/oui/tutorials/EUI48.html for more details. 6.2 MAC PDU headers process and is encrypted during transmission. The TSTID is released after the STID is assigned. The STID stays valid during the entire session. 6.2 MAC PDU HEADERS 6.2.1 Legacy Generic MAC Header Each MAC PDU in IEEE 302.16-2009 standard consists of a MAC header followed by a payload (also called SDU) and an optional Cyclic Redun