Case markers often distinguish between the various arguments of a predicate, such as the Agent and Patient. Three basic types of arguments are generally distinguished: the subject of a transitive clause, the object of a transitive clause, and the subject of an intransitive clause. 

<br><br>A few languages, like the Sudanese Dinka and Nuer, distinguish these cases with noun stem changes. 

<br><br><b>Reference</b><br>
Dryer, Matthew S.. 2008. Position of Case Affixes.
In Haspelmath et al (2008), chapter 51. Available online at <a href="http://wals.info/feature/51">
http://wals.info/feature/51</a href>.
