Here is my sentence:
The report further identifies two partial sets, which are not in themselves default sets but which one can—wholly or partly—combine with default sets A or B, or indeed with any permutation of options.
Should that have been “set A or B”? Is the set singular or plural?
Here is a simpler sentence on (I believe) the same principle:
When you reach customs, depending on whether you are a citizen, join queues A or B.
One could reword the latter sentence to evade the question, of course, but I seek an answer rather than a way to avoid an answer.
The second sentence is just something I made up for this question, but here is part of a third sentence, which comes from the same report as the first:
[It] earns exactly one of the adjudications respectively of Tables 3, 4, 5 or 6.
Should that be Table rather than Tables? Should that be and rather than or?
(Extra appreciation is given if you can provide a reference for your answer or, better, can quote a great writer to illustrate. If you cannot but still know the answer, though, please still give it. My copies of the AP Stylebook and the Little, Brown Handbook do not seem to answer the question.)
It should be “combine with the default set A or B” in this example. If you were to have options where each choice is a set of sets, then “the default sets” would be correct. In quick, relaxed English speech, this rule may not be followed. For example, with your second sentence, any person directing crowds toward queues may say “join queues A or B,” but it would be better to say “join queue A or B” as in “join the queue labeled A or the queue labeled B.” I would not use “join the queue A or B,” so there is some irregularity here.
A set is a singular entity, no matter how many elements it has, so the singular would be best, complete with a definite article for clarity. English speakers are used to phrases such as “combine with defaults sets A or B” in everyday speech and so this would probably remain unnoticed, even in a paper. I am almost certain both examples have been used in professional settings (not that that forbids a correct answer, but if there is an incorrect one, it is quite forgivable).
I hope this was of some help!
Edit: There is a sort of interesting thing about the word “or” in that in English, as in most other languages, it is inclusive. That is, it could also mean “and” if written without any additional quantifiers. If that is the case (if one does not forbid exclusivity), the “and” implies a multiple and would change “set” to “sets.” Perhaps this contradicts the earlier parts of my answer, but it is an important nuance that comes from additional thinking on it.
So, when you say “[It] earns exactly one of the adjudications respectively of Tables 3, 4, 5 or 6.” that “exactly one” is very important. This, to me, forbids the “and,” thus I believe “Table” would be best. However, many English speakers may not be used to this, having the inclusive “or” on the mind at most times, and may even find it a bit unnatural to see “Table” instead of “Tables” even in this context.