The Dative Case
editWhenever a sentence expresses something being done for someone, the beneficiary is put in the dative case, by suffixing the dative case particle .ir. Consider:
(1) Nanna.(i)r Šulgi.(e) e.Ø mu.na.(n).du = For Nanna, Shulgi built the temple
We see that the temple was built for Nanna, and hence his name is put in the dative case. As is standard, the initial /i/ sound is often lost when it occurs right after another vowel. (Nanna, incidentally, was the name for the moon god, also called Zuen.)
Also, somewhat mysteriously, the /r/ sound was often not written either! That means we're basically seeing Nanna but reading Nanna.(ir). However, it is often quite easy to tell when this is happening, and the meaning is usually clear whether or not the particle is actually written.
[Thomsen §175, Edzard §5.4.2.5]