The policy of each SE site is defined by its community, for each specific site like Buddhism.SE. In this topic (which is long, you probably don't want to read it all) I asked, and a few people discussed what 'moderation rules' or policy we do or do not want to implement, for questions asked on this site.
The desire or consensus which people suggested then (in that topic) is more liberal or more permissive about questions, than the policy on other SE sites that I know of.
Anyway, based on that input, I wrote the following to summarize what I think is this site's current policy (i.e. the policy which the three people who discussed it asked for) for moderating questions.
You can discuss or define this policy more if you like: post another answer, post a comment, vote, etc.