For the purpose of compatible interconnection of stations by way of a LAN using the token-passing bus access method this standard (1) Specifies the electrical and/or optical and physical characteristics of the transmission medium, (2) Specifies the electrical or optical signaling method used, (3) Specifies the frame formats transmitted, (4) Specifies the actions of a station upon receipt of a frame, (5) Specifies the services provided at the conceptual interface between the Medium Access Control (MAC) sublayer and the Logical Link Control (LLC) sublayer above it, (6) Specifies the actions, entities, and values used to manage the MAC sublayer and Physical Layer Entity (PLE). Within this standard the operation of a station is specified in terms of the layered model shown in Fig 1-1 and described in ISO 7498 : 1984 [13]. 1 Additional information on the 802 family of LAN standards can be found in IEEE Std 802- 1990 [9]. 2 Figure 1-1 also shows which sections of the standard specify interfaces between layers and which sections specify the operation of the layers themselves. Recommendations for frequency allocations for community antenna television (CATV) systems are subjects for national standardization and are outside the scope of this International Standard.