This is giving me dandruff and kidney stones. Here I was all happy that I could be able to work something out, and I'm ready to cry. Clearly, this is well over my head. Oh, well...
Anyways, the nearest thing I can figure to what you're asking about is:
Code:
<thing id="attrStr" name="Strength" description="Trololo-whatever" compset="Attribute" uniqueness="unique" isunique="yes">
<fieldval field="trtAbbrev" value="Str"/>
<fieldval field="trtMaximum" value="99"/>
<tag group="explicit" tag="5"/>
</thing>
And I can't find anywhere to put a simple <field> tag in there that won't make it either protest, or out and out ignore it.