I've seen a ПІЄ abbreviation in the answer on one of my questions today, and I had to ask for the explanation. It appeared to be Праіндоєвропейська мова.
I didn't know it, so I had to ask.
Perhaps, we need a thread where everyone will be able to add their abbreviations to make the understanding of answers easier?
Wiki-answer would be a good solution, as for me.
ПІЄ/PIE – is a very widespread abbreviation every linguist knows, just like OCS, "Old Church Slavonic". But since not only linguists visit our SE (StackExchange), the best strategy is to avoid abbreviations which are not explained in the text itself. As for me, I would never use unexplained abbreviations, if I use a long term often in my Q/A (question or answer), I will use it in full for the first time and write in brackets the abbreviation I ascribe to it, only then I will use the abbreviation in the text I write. That is the strategy I recommend to everyone. Naturally, common English language abbreviations like "&", "etc.", "e.g." do not count. As for the Internet abbreviations like "AFAIN" (for "as far as I know") and the like, I think they should not be used here at all and the moderators must correct them into the full phrases.
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.
IMHO is precisely in the answer, not in comment. And I.e., too. That's why I consider "I think we should not use abbreviations in answers" a too strong statement.
Commented
Mar 26, 2017 at 17:20
i.e. — you're right, there are some very common (not field-specific and not jargon/argo) abbreviations, like: i.e., etc, e.g., і т.д., і т.п., і т.і., etc. Probably they are exceptions (although OnlineCorrector recommends to replace some of them too).