When a Text construct or atom:content's type is "XHTML", require it to have a single xhtml:div as a child.
Given that common practice is to include this element, making it mandatory makes things clearer to both people who are producing consuming tools based on the spec, and people who are producing new feeds based on copy and paste.
Replace the paragraph on XHTML in section 3.1.1 of draft-ietf-atompub-format-05.txt with the following:
If the value of "type" is "XHTML", the content of the Text construct MUST be a single xhtml:div element. The xhtml:div MUST contain XHTML text and markup that could validly appear directly within an xhtml:div element. The xhtml:div element itself MUST NOT be considered part of the content. Receiving software which displays the content MAY use the markup to aid in displaying it. Escaped markup is interpreted as a text representation of markup, and MUST NOT be interpreted as markup itself.
<summary type="XHTML"><div xmlns="http://www.w3.org/1999/xhtml">This is <b>XHTML</b> content.</div></summary>
<summary type="XHTML"><xhtml:div xmlns:xhtml="http://www.w3.org/1999/xhtml">This is <xhtml:b>XHTML</xhtml:b> content.</xhtml:div></summary>
The following example assumes that the XHTML namespace has been bound to the "xhtml" prefix earlier in the document:
<summary type="XHTML"><xhtml:div>This is <xhtml:b>XHTML</xhtml:b> content.</xhtml:div></summary>
Replace the text of item 3 in section 4.15.3 with the same paragraph, and put the examples (and examples of the other types) after the list, with "summary" changed to "content".
This is the common method of including XHTML content in existing Atom feeds, so the impact on existing implementations should be minimal to nil.
if this pace gets accepted, I would ask for the same DIV container element for HTML content for reasons of symmetry.
SamRuby: the html content is different in that it is escaped content. It does not inherit the default namespace, and therefore does not have the practical problem of people getting the namespace wrong.