This standard provides definition, methods of measurement, and performance standards for radio equipment used in the Private (Dispatch) Land Mobile Services that employ C4FM or CQPSK modulation, for transmission and reception of voice or data using digital techniques, with or without encryption, with a frequency of 1 GHz or less. Document [R1] defines the requirements of both the Physical Layer and the Data Link Layer in the OSI reference model for the radio interface in which this equipment operates. Use of this standard is encouraged for any application of similar equipment with C4FM or CQPSK modulation. However, this standard is not intended to cover transceiver equipment employing any or all modulation types or access methods. Therefore, the applicability of this document to digital transceiver equipment other than that called out in the scope must be carefully examined.