A '''case role''' is any of the spatially-distinguished parts of a process. 

In the sentence, "You do that?", the subject "you" has the ''case role'' of `agent` and the object "that" has the ''case role'' of `patient`.

The meaningful case roles are dependent on the process. e.g.:
: for process ''crime'', case roles could be: `perpetrator` + `victim` + `evidence` + `modus operandi`; 
: for process ''burn'', case roles could be: `fuel`, `air`, `heat`

The term is used in natural language processing, but has its origins in linguistics. 

In practical terms for us, an instance of CaseRole can be just about any type, from parts of speech (subject,object), participants in a process (agent,patient), or other relationship names (mother,father). 

Analysis of CaseRole from the general (subject) to the specific (my mother) may be performed by a reasoning engine. Conjecture of applicable CaseRoles may be formed by pattern matching (or other non-logical means), then proved (or disproved) by logic systems. 

References: IEEE SUMO 
http://www.ipsj.or.jp/members/SIGNotes/Eng/01/1995/107/article012.html
http://www.uoregon.edu/~delancey/papers/bls91.html