(The rest of this post assumes APML is XML, but it doesn't have to be.)
Here's an pseudo xml example, where you just use a long URI for each:
<concept key="urn:apml-org:blue%20cats" .../>
<concept key="urn:apml-org:red%20dogs" .../>
However, these would explode combinatorially. Some sort of compound
concepts seem better:
Here's psuedo xml example for nesting concepts:
<concept key="urn:ampl-org:cats" ...>
<concept key="urn:apml-org:blue" value=1/>
</concept>
<concept key="urn:ampl-org:dogs" ...>
<concept key="urn:apml-org:red" value=1/>
</concept>
Re: Type Attribute
I'm not a big fan of the proposed "type" attribute for concepts, which
has been suggested would allow for type="Person/Location/Music", etc.
First, enumerating the "types" puts APML right back into defining
ontologies beyond the attention ontology. Second, a technical
problem: if you use an xml attribute for "type", that means that the
concept can only have type, and I couldn't use "type" to be interested
in dogs that are both red and hot.
--Mason