* Before the establishment of the Communications Authority (CA) on 1 April 2012, the specifications prescribed by the Telecommunications Authority (TA) were named as HKTA specifications. From 1 April 2012 onward, revised versions of existing HKTA specifications and new specifications prescribed by the CA will be named as HKCA specifications. For the avoidance of doubt, unless the specific issue number of the HKTA specification is explicitly specified, reference in any document to HKTA specification shall be construed as including reference to the corresponding HKCA specification as may be revised from time to time. In addition, reference in any document to HKCA specification shall be construed as referring to the corresponding HKTA specification if the HKCA specification under reference is not yet present.