Full Idea
I will propose that events are said to constitute one type of states of affairs, and propositions another
Gist of Idea
I propose that events and propositions are two types of states of affairs
Source
Roderick Chisholm (Person and Object [1976], 4.1)
Book Reference
Chisholm,Roderick: 'Person and Object' [Open Court 1976], p.114
A Reaction
I would much prefer to distinguish between the static and the dynamic, so we have a static or timeless state of affairs, and a dynamic event or process. Propositions I take to be neither. He really means 'facts', which subsume the whole lot.