It is important to develop a strong terminology for the polyglot spec .

The proposed, new title ("Polyglot Markup: HTML-Compatible XHTML Documents") introduces some new wordings: "Polyglot Markup", "HTML-compatible" and "HTML-compatible XHTML document". Please build these and simlar wordings into the body text. Also, the reaction to the phrase 'polyglot document' was that it was possible to misunderstand and so, even in the text, it should be avoided both for that reason and in order to instead underline the phrases from the titlte.

I also believe 'HTML polyglot' as synonym for 'HTML-compatible XHTML documents' is worth using in the text (even if it did not work in the title).

As example of an important text, I suggest the following amendment of the Abstract, as an example of how the suggested formulations can be built into the spec text:

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This specification defines Polyglot Markup, an HTML-compatible XHTML document format. Documents of this kind are also known as HTML polyglots. An HTML polyglot is an HTML5 document which is at the same time an XML document and an HTML document. HTML polyglots that meet these constraints are, per the HTML5 specification, interpreted as compatible, regardless of whether they are processed as HTML or as XHTML. An HTML polyglot is obligated to have an XML- and HTML5-compatible doctype, to use namespace declarations, and to use a specific case—normally lower case but occasionally camel case—for element and attribute names. HTML polyglots use lower case for certain attribute values. Further constraints include those on empty elements, named entity references, and the use of scripts and style.
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