Map element attributes in LwDITA (id and domains)

More minor items based on reading the grammar files + browsing in Chris's tool.

I see that @id is required for maps - not sure if this is intentional or not, as it's not required in base DITA maps. Is there a reason to require an ID here?

We have added a @domains token for most of our domains, but not for <keydef> (which is correctly defined as part of a domain). As long as we're adding tokens for the other domains, we should be adding a token in map/@domains:
(map mapgroup-d)

The topic element adds a domain token "(topic xdita-c)" which can be used to identify topics that comply with LwDITA. It basically means "This document complies with the lightweight DITA constraint so feel free to apply those rules." We should have a similar token in maps to identify maps that comply with LwDITA:
(map xdita-c)

Regards,
Robert D. Anderson 
DITA-OT lead and Co-editor DITA 1.3 specification,
Digital Services Group 

E-mail: 
Digital Services Group 

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