In any case, I reject the idea that we should just drop the table markup altogether and use inline variablelists. In most of these sections there is a very clear separation between the table contents (with per-function or per-operator details) and the surrounding commentary, which deals with more general concerns. That's a useful separation for both readers and authors, so we need to preserve it in some form, but the standard rendering of variablelists won't. (Our existing major use of variablelists, in the GUC chapter, works around this basically by not having any "surrounding commentary" ... but that solution doesn't work here.)
There is also value in being able to say things like "see Table m.n for the available operators for type foo".
The HTML definition list under discussion looks like this:
<dl>
<dt> term 1 </dt>
<dd> description 1 </dd>
<dt> term 2 </dt>
<dd> description 2a </dd>
<dd> description 2b </dd>
</dl>
So the enclosing <dl> element has the same role in the overall document as the <table>, and could be styled to set it apart from the main text and make it clear that it is a single unit (and at least in principle could be included in the "table" numbering). In the function/operator listing use case, there would be one <dd> for the description and a <dd> for each example. See:
If we were only concerned with HTML output then based on the desired semantics and appearance I would recommend <dl> without hesitation. Because of the need to produce PDF as well and my lack of knowledge of the Postgres documentation build process, I can't be so certain but I still suspect <dl> to be the best approach.
