In trying to describe PeopleTags and ImageRegionTags I realized there is a more elegant unified tagging scheme that could/should be put in place. It is wildly more complex to define properly, thus will take more time and require a more complex schema. The up side is it should be forward thinking enough to be compatible with most future tagging capabilities for many years to come.

I will continue to modify / refine this description as time and inspiration allow.

Summery

Create a Tagging structure in  XMP that allows for complex and simple tags to be in place. Something like the following:

Tag

• keyword: the tag used in the exif/ITPC section of the header to refer to this tag. Placed in exif for reverse/basic compatibility
• Image Region: most likely a rectangle defined by a center point (percentage) and width x height (also percentage)
• Type of tag: (closed set, to be expanded carefully)
  • People
    • ID value, ID type (have a local issued id, then several other optional once, such as MicrosoftID, Facebook, Email, etc)
  • Non-People single personified instance (pets, fiction characters)
    • ID value, ID type (extra id types such as owner local ID, or referenced work)
  • non-personified Single instance non-location(things, example Blarney stone, St. Michaels Cathedral, etc.)
    • ID value, ID type (local ID, and ID of location if relevant)
  • location
    • ID value (local only)
    • gps center or entrance point (possibly a bounding rectangle or other shape)
  • Concept
    • Local ID (to prevent homonyms and separate context from overlapping)
    • Definition or Clarification to help with portability
  • Note
    • if given a region the note is applied there
    • if not given a region it is the description exif/iptc tag
    • if it is given a region but is the only note it is also put in the description exif/iptc tag
    • notes should allow for embedded simple html including bold italic underline and hyper-link, maybe lists.
  • Link
    • If no region is present it is a general reference link (maybe listed below the image)
    • If a region is present, highlighting should expose where the link is to, clicking should follow it. (possibly also listed below image)

End of Tag

To work properly this would also be dependent on:

• Local listing of the local issued IDs as well as other relevant information to each instance.
• Concepts should have a semantic map as well as a local listing (perhaps there is a human language semantic map that can be inherited as a strong start)
• People could have a relationship tree similar to a semantic map, illustrating their relationship to each other.