OPS has conflicting definitions of "out of line xml islands".
|Component:||Open Publication Structure (OPS)|
|Status:||completed @ 2.0.1|
Out of line XML conformance forbids use of "application/xhtml+xml" for out of line xml islands:
A document is an Out-of-line XML Island Content Document if and only if:
1. it is a well-formed and valid XML document (as defined by XML 1.1 according to its schema); and
2. it is encoded in UTF-8 or UTF-16; and
3. it has a MIME media type other than application/xhtml+xml, text/x-oeb1-document or application/x-dtbook+xml.
The definition in OPS 2.6.2.
An Out-Of-Line XML Island is a complete XML document that is not authored in one of the Preferred Vocabularies or uses an Extended Module in an otherwise Preferred Vocabulary document. Including an Out-Of-Line XML Island requires several declarations in various parts of the Publication.
And the XHTML guideline is that the "application/xhtml+xml" is for the whole XHTML family of documents.
"... This media type must be used when writing documents using XHTML Family document types that add elements and attributes from foreign namespaces, such as XHTML+MathML ..."
So, the issue arises if I want to author a document that uses an extended module (say, MathML), the files that use XHTML+MathML would be out of line XML according to the definition in OPF sec 1.2 and OPS sec 2.6.2. Unfortunately there's no media type that could be used. (application/xhtml+xml would be right according to the XHTML spec, but would mean it's out of compliance according to OPS 220.127.116.11.)
I propose we resolve this by altering Section 18.104.22.168 of OPS to read:
"it has a MIME media type other than application/xhtml+xml (and is not an extended XHTML module), text/x-oeb1-document or application/x-dtbook+xml."