Full Idea
Tropes are abstract entities, at least in the sense that more than one can be in the same place at the same time (e.g. redness and roundness). But they are not universals, because they have unique and particular locations.
Gist of Idea
Tropes are abstract (two can occupy the same place), but not universals (they have locations)
Source
Cynthia Macdonald (Varieties of Things [2005], Ch.3)
Book Reference
Macdonald,Cynthia: 'Varieties of Things' [Blackwell 2005], p.89
A Reaction
I'm uneasy about the reification involved in this kind of talk. Does a coin possess a thing called 'roundness', which then has to be individuated, identified and located? I am drawn to the two extreme views, and suspicious of compromise.