"General Scope The present document defines the radio-frequency interface specifications for high-speed Data-Over-Cable Systems. They were developed for the benefit of the cable industry@ including contributions by operators and vendors from North America@ Europe@ and other regions. The source material was the DOCSIS? ""Data-Over-Cable Services Interface Specifications@ Radio Frequency Interface Specification 1.1 Interim 08 01/05/02""@ for which the latest published version can be found at www.cablemodem.com. There are differences in the cable spectrum planning practices adopted for different networks in the world. Therefore two options for physical layer technology are included@ which have equal priority and are not required to be inter-operable. One technology option is based on the downstream multi-programme television distribution that is deployed in North America using 6 MHz channelling@ and supports upstream transmission in the region 5-42 MHz. The other technology option is based on the corresponding European multi-programme television distribution and supports upstream in the region 5-65 MHz. Although both options have the same status@ the first option was documented earlier and the second option introduced at a later time as an amendment@ resulting in the document structure not reflecting this equal priority. The first of these options is defined in clauses 4@ 6@ 7@ C.1.1.1 and annex G@ whereas the second is defined by replacing the content of those clauses with the content of annex N. Correspondingly@ [ITU-T Recommendation J.83]@ [NCTA] and [SMS] apply only to the first option@ and [EN 300 429] only to the second. Compliance with the present document requires compliance with one or other of these implementations@ not with both. It is not required that equipment built to one option shall inter-operate with equipment built to the other. 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 clauses 4@ 6@ and 7 might be deployable within an 8 MHz channel plan. Compliance with frequency planning and EMC requirements is not covered by the present document and remains the operators' responsibility. In this respect@ [FCC15]@ [FCC76]@ and [EIA-S542] are relevant to North America and [EN 50081-1]@ [EN 50082-1]@ [EN 50083-2]@ [EN 50083-7]@ and [EN 50083-10] are relevant to the European Community. The option of clauses 4@ 6 and 7 together with clause C.1.1.1 and annex G is required to be backwards compatible with an earlier version of that technology [DOCS9]@ whereas the option of annex N was not included in [DOCS9] and therefore is not required to be backwards compatible with [DOCS9]. Any reference in the present document to the transmission of television in the forward channel that is not consistent with [EN 300 429] is outside the normative scope as only [EN 300 429] is used for digital multi-program TV distribution by cable in European applications. Requirements for safety are outside the scope of the present document. Safety standards for European applications are published by CENELEC. NOTE 1: Examples of such CENELEC product safety standards are [EN 60950] and [EN 50083-1]. NOTE 2: For CENELEC safety categories of interfaces@ see [EG 201 212]."