[imsc] foreign namspace usage is underspecified

mikedo has just created a new issue for https://github.com/w3c/imsc:

== foreign namspace usage is underspecified ==
The only conformance text on the subject is:

6.2 Foreign Element and Attributes 
A Document Instance MAY contain elements and attributes that are 
neither specifically permitted nor forbidden by a profile. 
A transformation processor SHOULD preserve such elements or attributes
 whenever possible.

G and H have some brief informative material.

The XML schemas are informative and make various assumptions not 
traceable to the spec.

FYI, TTML has no conformance language like either the above or the 
following additional provisions that I believe are needed for document
 interop when extending it with foreign namespaces. 

1. Where exactly can they be used?  Everywhere?
    a. Specifically for <sequence>, do they follow, lead, or can they 
be placed between any elements?
2. What namespaces are permitted?  Is ##other assumed or ##any?
3. What processContents setting is to be used(this affects the 
validation behavior on future schemas and extended documents)?
4. (probably other things I have not thought about like union)

Please view or discuss this issue at 
https://github.com/w3c/imsc/issues/213 using your GitHub account

Received on Friday, 10 February 2017 18:59:20 UTC