The "/technoteedit" page:

Revise or create a technical note (formerly called an "event").

Required query parameter:

   name=ID           Hex hash ID of the technote. If omitted, a new
                     tech-note is created.

POST parameters from the "Cancel", "Preview", or "Submit" buttons:

   w=TEXT            Complete text of the technote.
   t=TEXT            Time of the technote on the timeline (ISO 8601)
   c=TEXT            Timeline comment
   g=TEXT            Tags associated with this technote
   mimetype=TEXT     Mimetype for w= text
   newclr            Use a background color
   clr=TEXT          Background color to use if newclr

For GET requests, when editing an existing technote newclr and clr
are implied if a custom color has been set on the previous version
of the technote.