The paragraph states as follows:
"Not all channels listed in the Audio Channels column of a given soundfield group in SMPTE ST 428-12 need to be present in the sound track file, but only those channels listed in the Audio Channels column for a given soundfield group may reference that SoundfieldGroupLabelSubDescriptor instance."
Annex A is normative. If the above is a normative statement, then the use of "need not" could be indicated here. Potential reword:
"All channels listed in the Audio Channels column of a given soundfield group in SMPTE ST 428-12 need not be present in the sound track file, but only those channels listed in the Audio Channels column for a given soundfield group may reference that SoundfieldGroupLabelSubDescriptor instance."
The paragraph states as follows: "Not all channels listed in the Audio Channels column of a given soundfield group in SMPTE ST 428-12 need to be present in the sound track file, but only those channels listed in the Audio Channels column for a given soundfield group may reference that SoundfieldGroupLabelSubDescriptor instance."
Annex A is normative. If the above is a normative statement, then the use of "need not" could be indicated here. Potential reword: "All channels listed in the Audio Channels column of a given soundfield group in SMPTE ST 428-12 need not be present in the sound track file, but only those channels listed in the Audio Channels column for a given soundfield group may reference that SoundfieldGroupLabelSubDescriptor instance."