DOM2 HTML - HTML Transitional support

Hello,

This is my first time in this list. I've been searching the archives and
FAQ's for my question, but have been unsuccessful to anything about it.
Please, excuse me if I just wasn't good enough ;)

In DOM2HTML specification, section 1.1, it says:
"...In many cases, these enhancements are not applicable to a general DOM
because they rely on the presence of a predefined DTD. The transitional or
frameset DTD for HTML 4.01, or the XHTML 1.0 DTDs are assumed.".
From this sentence I understand that DOM2HTML has been specified to cover
the whole definition of transitional and frameset DTD's.

My question is:
A strictly-compliant DOM2HTML implementation should always support the whole
DOM definition, regardless of the corresponding HTML inplementation is
strict or transitional?
I mean, supposing a future user agent that accepts only HTML strict
(what should progressively happen with all HTML processors), and implements
DOM2HTML, should it implement also the DOM features related only to
transitional or frameset HTML?
Could, for example, a target attribute be added to an "a" element?
If so, should, then, the user agent process and render correctly all these
"transitional" features just cause DOM2HTML still specifies them?

In my opinion, this is not clear in the specification and people are making
assumptions about it.
I first found this in an article about standards-compliant popup links. In
it, it's suggested to use rel="external" to mark such links (strict
HTML-compliant) and then use DOM to add target="_blank" to those links. Near
the end of the article it's also argumented that, while transitional HTML
will dissappear in future and target attribute won't be supported anymore
for anchors, target="_blank" will probably still be supported by user
agents, as it's still specified in the DOM standard. Is he right?

The link to this article is:
http://www.sitepoint.com/article/standards-compliant-world

Thanks a lot in advance,

Juan Farré