I think we should not use abbreviations in answers. To make them readable for wide audience.
Of course, it is not crucial — better an answer with abbreviations than no answer (or a bad answer). And not always easy: sometimes we hurry, sometimes we mistakenly consider something as obvious (e.g. SUM-11) and intuitively don't even realize the problem with it. But the best is not to use abbreviations (I mean: not explained within the post itself). In practice: to write as you can, but remove/describe abbreviation as soon as somebody asks "what it it" — instead of considering it as problem of those who doesn't know something.
I.e. it's ok to make a list of abbreviations for ourselves (to share that knowledge between ourselves). But it's not ok to make a list of abbreviations with the intention "to use later these abbreviations in questions and answers without explanations, pointing users to that list instead of correctly decorating the posts". In my humble opinion.