Proposal: New State - Renderer

Hypothes.is currently stores annotations made on PDF's via the PDF.js
viewer. We currently store these as we would any other web page annotation
and use our own internal knowledge about our system to re-anchor
annotations made on a PDF by assuming the rendering is via PDF.js--however,
as these annotations "move" around the Web (and as I attempt to express
them in Web Annotation) we've hit a wall where we have the need of a new
expression State.

http://www.w3.org/TR/annotation-model/#h-states

Currently, there are two sub-classes of State: TimeState and
HttpRequestState.

What I'm needing, is something more like `generator` in Creation
Information:
http://www.w3.org/TR/annotation-model/#h-creation-information

I believe (at first glance/dig through) that we have sufficient
expressiveness in the Creation Agents section:
http://www.w3.org/TR/annotation-model/#h-creation-agents

If we apply that to a new State sub-class--say RendererState or some
such--then I believe I can express what's needed as we create these PDF
annotations on specific versions of PDF.js such that others (and ourselves
later) can benefit from the knowledge we store in these annotations thereby
making them easier to re-anchor, find, etc.

If this sounds correct or at least interesting, I'm happy to write up a
more formal expression of it as a pull request on the current model.

Thanks!
Benjamin
--
Developer Advocate
http://hypothes.is/