I didn’t want to say that handling of entity references would be trivial—but only that a fixed entity set does not make it easier. In which contexts (not in code spans, for example) an entity reference should be recognized as such or should be treated as character data is independent from the specific name of the entity and from the replacement text, if any.
Talking about “recognizing an entity reference” is a bit misleading, because basically this means the opposite for the implementor than it does for the user:
-
A lexical item that “looks like an entity reference” in a code span in CommonMark actually must be recognized by the processor and must be “escaped”, so that later the user (ie the user’s browser, say) does not recognize it as an entity reference;
-
And vice versa: Whether or not some substrings in an HTML block “look like an entity reference” can be ignored by the processor, because these will be recognized later by the user (in her browser or similar tool).
At least that’s how I understand this confusion …