Common multi-channel setup is 5.1 and 7.1 with rear speakers.
Thus only setups that include SPEAKER_SIDE_LEFT and SPEAKER_SIDE_RIGHT
needs the marking as not common (or "side" use), while it stays the
true Side setup (with side speakers) by its internal meaning.
This "side" is named "surround" by Microsoft. To not confuse users and
translators, it is wise to use "Side" mark next to format name.
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