EIA/TIA Category Specification provide for the following cable
     transmission speeds with specifications (Note prior to Jan94
     UL and Anixter developed a LEVEL system which has been dropped
     or harmonized with the CATEGORY system);

 Category 1 = No performance criteria
 Category 2 = Rated to 1 MHz (used for telephone wiring)
 Category 3 = Rated to 16 MHz (used for Ethernet 10Base-T)
 Category 4 = Rated to 20 MHz (used for Token-Ring, 10Base-T)
 Category 5 = Rated to 100 MHz (used for 100Base-T, 10Base-T)

     UL LAN Cable Certification Program - Underwriters Laboratories
     publication 200-120 30M/3/92, 1992 [characteristics of Cat 3-5 UTP]