Locking custom metadata

Locking fields may defeat the purpose of running an auto-update and lead to some frustration, but we are interested in hearing whether making additional edits after an auto-update is a common experience.

W.r.t. crowd-sourced metadata - this is not something we are currently planning, for a number of reasons (see this thread). Mendeley has been doing this and the result is, in my opinion, a mess.