As @elliot mentioned, the key can be any (reasonable) string starting with field_
So while you could manually generate IDs with uniqid(), it might make more sense to use something that has meaning and you know is unique. Like maybe field_book_author or field_user_message_body where the first part might relate to the object type this is attached to.
@elliot do you see any possible issue with this? Presuming it isn’t too difficult to make those key names unique.
Just a thought 🙂
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