Metadata on pictures/photographs
DateTime - Roughly speaking, the earliest of file mtime, EXIF original creation, and other similar tags.
Location - User tagging, or possibly even GPS location in the EXIF tags
EXIF tags - Data comes from the camera and describes many aspects of how the picture was taken.
User tags - Three forms?
BADGERS (bare tag?)
LOCATION=singapore (valued)
PERSON=rob PERSON=rose (multivalued?)
This seems klunky, and what the hell are bare tags for?
Maybe something more like tag sections
First pass on a photo you can just list tags
Badgers, Singapore, Rob, Rose
The system then can attempt to recognize and parse tags into sections based on other data
Badgers, Location:Singapore, Person:Rob, Person:Rose
Then I run into the problem of equivalent tags
Location: SFO and Location: San Francisco should be semantically the same thing for searching