The bulk of the proposal is (currently) in a PDF; see attached file. The proposal comes from the Google teams working with the existing Event markup, and has been checked by the other schema.org partners prior to publication. See PDF for full details of the proposal.
A slightly revised proposal was updated in May 2013, and includes improvements for the repeating events model. A later simplification was posted Oct 1st 2013, removing some of the complex event repetition model.
Event schema.org proposal
Goals and associated spec modifications (Oct 2013):
- Support markup for canceled or rescheduled events
- Add three new properties: eventStatus, previousStartDate, previousEndDate
- Allow more event sites to mark up event categories
- Add one new property: eventCategory. Deemphasize existing categorical subtypes of Event.
- Document how to link to official pages
- Use the “url” and “sameAs” properties (this is not a modification; these features already exist in schema.org)
- Model sold-out or nearly sold-out events
- Add two new values, “Limited” and “SoldOut”, to the schema.org/ItemAvailability enumeration
- Oct 2013 version File:Events-proposalforupdatedschemav3-External.pdf (pdf)
May 2013 version (obsolete) File:Events-proposalforupdatedschemav2.pdf (pdf)
See also: [ActivityActions], where the Action type shares some Event-like structures.
Note from WebSchemas/Singularity a property re-naming (in progress, Mar 2012):