ISO 21460:2007 defines the Proximity-1 space link protocol physical layer. It specifies the channel connection process, provision for frequency bands and assignments, hailing channel, polarization, modulation, data rates, and performance requirements. Currently, the physical layer only defines operations at UHF frequencies for the Mars environment. The coding layer is defined in ISO 21459. The data link layer is defined in ISO 22663. ISO 21460:2007 does not specify individual implementations or products; implementation of service interfaces within real systems; the methods or technologies required to perform the procedures; or the management activities required to configure and control the protocol. The scope and field of application are furthermore detailed in subclause 1.3 of the enclosed CCSDS publication.