The Financial Industry Business Ontology (FIBO) defines the sets of things that are of interest in financial business applications and the ways that those things can relate to one another. In this way, FIBO can give meaning to any data (e.g., spreadsheets, relational databases, XML documents) that describe the business of finance.
This is a gap in the financial instruments ontology - both concepts need to be incorporated, and the legs of any swap also need this concept.