Icon selection, by property queried
Fragment of a discussion from Help talk:Google Maps format
Ok, you are not understating how Semantic Compound Queries work. What you're trying to do is quite understandable, as it would make more sense then the approach you'll have to take, since what you're trying now is sadly enough not possible.
You cannot switch on a property, you have to switch on queries. You thus need two queries, each with a different property. See Semantic Maps examples/Compound queries for an example.
I'd love to see switching on properties in SCQ :)