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>In <b>case-symmetric</b> languages like Turkish, all full NPs inflect the same case categories, regardless of type:

<br><br>a) <i>kitap</i> 'book.NOM,' <i>kitap-i</i> 'book.ACC,' <i>kitab-in</i> 'book.GEN,' <i>kitab-a</i> 'book.DAT,' etc.
<br>b) <i>ben</i> '1SG.NOM,' <i>ben-i</i> '1SG.ACC,' <i>ben-im</i> '1SG.GEN,' <i> ban-a</i> '1SG.DAT,' etc.              

<br><br>A language marked 'no' may demonstrate several varieties of case-asymmetry.  This occurs when at least one NP-type inflects for more or fewer cases than those used in the language's standard inventory (quantitative asymmetry).  A language is also considered case-asymmetrical when the domains of its cases are markedly different across NP-types (qualitative asymmetry).

<br><br><b>Reference</b><br>
Iggesen, Oliver A.. 2008. Asymmetrical Case-Marking.
In Haspelmath et al (2008), chapter 50. Available online at <a jref="http://wals.info/feature/50">
http://wals.info/feature/50</a href>.
 