The National Electrical Code (1988 revision) establishes multiple level
definitions for performance specifications of twisted pair wire, as follows.
Voice Communications Cables
CM: Voice communications cable for telephone installations.
CMR: Voice communications cable for use in building risers.
CMP: Voice communications cable for use in air plenums.
Data Communications Cables
CL2: Data communications cable for all equipment except telephones.
CL2R: Data communications cable for use in building risers.
CL2P: Data communications cable for use in air plenums.
DCC
