Class D (1995): This is the maximum rating of the presently only published ISO/IEC and CENELEC standard. Please note that the permanent link and channel requirements are not published in these standards, but only the very impractical and soon outdated "link" requirements.

Class D (1999): This is the maximum rating of the amendments to ISO/IEC and CENELEC standards which are expected for publication in September 1999. These documents define permanent link and channel configurations and performances, and include both new parameters and more tight limits.

Class D (2000): This is the 100 MHz rating of the 2nd editions of ISO/IEC and CENELEC standards. 2000 could become 2001 depending on the release date of the standards. These documents are expected by 3P to define more strict limits to a number of Class D (1999) parameters, corresponding to the American Cat. 5e requirements (with supplementary ISO/IEC and CENELEC requirements).

Class E: This is the 200 MHz rating of the 2nd edition of ISO/IEC and CENELEC standards.

Class F: This is the 600 MHz rating of the 2nd editions of ISO/IEC and CENELEC standards.

Furthermore, the TIA/EIA standardisation operates with basic link and channel standardisation, which unfortunately will be different than the ISO/IEC and CENELEC requirements. A fundamental difference will be that TIA/EIA basic links includes the hand-held field tester measurement cords in the permanent link performance. This is unacceptable to ISO/IEC and CENELEC as the tester cords will never be part of the installation and therefore it will possibly give mis-information about the permanent link performance.

Except for this major difference and a number of smaller conflict points the following correlation between ISO/IEC / CENELEC and TIA/EIA cabling standardisation applies:

ISO/IEC & CENELEC TIA/EIA
Class D (1995) ~ Cat. 5
Class D (1999) ~ Cat. 5 Addendum 4
Class D (2000) ~ Cat. 5e
Class E ~ Cat. 6
Class F ~ Not specified