@MartinSleziak Sorry to ask you something you probably already explained somewhere (it's motivated by the arithmetic logic thread). Assume an existing tag is A, and tag B doesn't yet exist. Which operations (from mods) can be done with immediate effect is that A (at least apparently) is replaced with tag B in every post? (...)

(...) One such operation (a) is to make A a synonym of B. In such an event, every future use of tag B is automatically "replaced" with A. This has been done in many cases. Is there an operation (already performed?) (b) in which, as a result, tag A is reset to 0? that is, allowing future uses of tag A, or future (= posterior to operation) manual addition of tag A to questions with tag B? or any other variant (still with the immediate effect of making tag A at least apparently disappear)?

(Note: I have in mind A: peano-arithmetic and B: theories-of-arithmetic. It seems at short term that the best option is to replace A with B and wish to amend my Meta post accordingly, but I'd need feedback for this technical point.)