There are differences in the cable spectrum planning practices adopted for different networks in the world. Therefore three options for physical layer technology are defined, which have equal priority and are not required to be interoperable. One technology option is based on the downstream multi-programme television distribution that is deployed using 6 MHz channelling, and supports upstream transmission in the 5-42 MHz region. The second technology option is based on a multi-programme television distribution using 8MHz channel spacing and supports upstream in the 5-65 MHz region. The third technology option is based on 6MHz channel spacing and supports upstream in the 10-55 MHz region.. The first of these options is defined in Sections 4, 6, and 7, whereas the second is defined by replacing the content of those sections with the content of Annex F. Compliance with this document requires compliance with only one of these implementations. All three technology options are defined in [ITU-T J.122]. It is not required that equipment built to one option shall interoperate with equipment built to another.

These optional physical-layer technologies allow operators some flexibility within any frequency planning, EMC and safety requirements that are mandated for their area of operation. For example, the 6 MHz downstream-based option defined by Sections 4, 6, and 7 might be deployable within an 8 MHz channel plan.