 The terrestrial tier is based on the Joint Tactical Radio System (JTRS) Ground Mobile Radio (GMR) and Handheld, Manpackable, Small Form Factor (HMS) radios running two transformational waveforms, the Soldier Radio Waveform (SRW), and the Wideband Networking Waveform (WNW).Both radios will also run select legacy waveforms to provide current force and Joint interoperability.The standards layer is the foundation of the FCS (BCT) network.