This one has been in my head for quite a long time.
Right now, we have free text, which means it is not machine actionable. I'd like to have the ability to populate a list of acceptable value, such as Resolved Abbreviation, Unresolved Abbreviation, Corrected Spelling, Original Spelling, Special Character used (eg. MUFI), things like that. It would go alongside the transcription guidelines but would make the whole thing a little more machine actionable.