Category name
Rendering
Is this top-level category or a subcategory?
Not sure.
Description of it’s purpose and which open mapping groups will serve
Anything rendering, between importing data, designing maps with various tools (mapnk, kosmtik, etc), to serving them (mod_tile, etc).
Why this new category is needed instead of being hosted as part of the existing ones?
Current Categories are not specific enough and
Is this a new space or it’s already existing in other platform(s)? Where?
Rendering maps / OpenStreetMap Forum is the only one I know.
What the current volume of messages in the former platform (per week/per month)
I don’t know how to get that information. What I can see is ‘latest answers’ which clocks at about 2-4/mo.
Is there a transition plan for the old platform to this new one? (please link or describe)
I don’t know, but since it’s in the forums, I would guess so.
(Optional) A link or list of the category specific guidelines
https://community.openstreetmap.org/faq#guidelines
List the usernames of the category moderators
None commited, except maybe me. Maybe I can get some support once this request is up.