1.1 Purpose This document, which all other MOST Specifications relate to, is the main specification of MOST (Media Oriented System Transport). 1.2 Scope This document contains the specification of the MOST application layer and the MOST network layer. This specification is speed grade independent. However, it is not fully backward compatible to the existing speed grades MOST25 and MOST50 as described in the MOST Specification Rev. 2.5. In some cases a differentiation between specific implementations (speed grade, physical interface) is necessary. The following terms are used to mark corresponding passages.