We have two sorts of domain specializations, "classic" and "attribute",
but we don't call "classic domain specializations" that, they are just
"domain specializations" because they came first.
a(module module) is correct for attribute domains and in that case
"topic" and "map" do not enter into it. All attribute specializations
are based on either @props or @base.
An example domains attribute value could look something like this:
(topic ui-d) (topic sw-d) (topic pr-d cpp-d) a(base newattrname)
a(props someothernewattrname)
-Jeff
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