General

the ids should probably be fully resolved (http://manuscripts.io/schema/mp-section.json)
what is a sessionID again? In the export the hardcoded id MPColors don't have a sessionID
can preferredXHTMLElement be enumed
MPPageLayout has embeddedNumberingStyle which is an MPNumberingStyle.
- It has a priority and I have no clue how.

Specific files

definitions/
- scalars.json
  - timestamp
    - FIX: arbitrary minimum and maximum values.