Describes the portion of the Power Line or RF Physical Layer that interfaces to the Medium Access Control (MAC) Sublayer and to Layer System Management (LSM). This sublayer is called the Power Line/RF Symbol Encoding (PL/RF SE) Sublayer. The PL/RF SE Sublayer provides two primary functions: (1) Accepts symbol transmission requests (PH CC DATA.request service primitive) from the MAC Sublayer, converts the symbols into correct medium state change timing (spread spectrum waveforms), and produces requests (M STATE.request) for state changes on the physical medium. This function is symbol encoding. (2) Accepts state change indications (M STATE.indication service primitive) from the Control Channel Medium Dependent Physical (MDP) Sublayer, converts the time between state changes to symbols, and produces indications of symbol reception (PH CC DATA.indication) for the MAC Sublayer. This function is symbol decoding.