When to inc_ref / dec_ref?

[xlc]

There is an introduction of inc_ref / dec_ref in frame_system recently.

It is been called by some of the substrate pallets (e.g. democracy, recovery), but not some others (e.g. identity, society).

There isn't much documentations about when a custom pallet should use inc/dec the reference of an account.

Any quick guidance? and some extensive documentations followup?

(Is this kind of question belong to here or substrate-developer-hub?)

[bkchr]

CC @gavofyork