This week, CM JNat posed the following question in comments on a post about restoring the ID content that was obliterated during the ID ban:

should the unlocking, undeleting, and reopening be applied to all questions that fall under that criteria, or are there additional criteria (date, score, etc.) that should be taken into consideration here?

In the ensuing discussion, two proposals were put forward:

I believe that any question previously closed for being an identification question should be unlocked, reopened, and undeleted. -- galacticninja

I would strongly advise to apply this only to the questions that were mass-closed/deleted/locked during the ID ban in '15 for now. -- NapoleonWilson

These two different proposals both have their pros and cons, but it's not easy to discuss them deeply in comments, nor to get an idea of consensus as comments can only be upvoted and not downvoted. In the interests of keeping things constructive (as reminded by CM BellaBlue), I've branched this discussion out into a new meta question, where different proposals can be posted as answers and voted upon, in order that there can (hopefully) be a clear consensus for CMs to implement before the end of the year. (The second half of this answer was edited in after it had already got upvoted, so that doesn't count as consensus for galacticninja's proposal.)

Given that older ID questions are to be restored, which set of questions should this apply to, and what level of restoration (reopening/undeleting/unlocking) should be done?

As a point of order: unlocking can only be done with diamond powers (mods/CMs); undeleting can be done by high-rep users unless the post was diamond-deleted, in which case it can only be done with diamond powers; reopening can be done by high-rep users as long as the question is unlocked. These facts may affect which of these acts should be requested from CMs in an en-masse operation.