The Ergative Case edit
Sumerian, as mentioned before, is a split-ergative language. Ergativity is simply one way in which languages mark certain phrases in a sentence as the subject or object, for instance. In ergative constructions, we usually mark the "agent", or whoever is doing the action, differently than the "patient", namely whoever the action is being done to. An example might be the sentence Achilles eluded Paris. Here, it is Achilles who is doing the eluding, and is the Agent, and Paris is the Patient -- the one who is being eluded.
Now, not all sentences have a patient. Intransitive sentences (as opposed to the transitive example above) are such constructions, and an example might be Socrates slept. Here, we only have a Subject, namely Socrates.
The distinguishing feature of ergative languages is that the Patient and Subject are always in the same case (the absolutive) while the Agent gets its own case (the ergative). In Sumerian, the ergative case is denoted by the suffix .e. In (1) above, notice that Šulgi.(e) is the Agent of the action (he is building the temple), so we place the ergative suffix after his name. (Again, we see the typical Sumerian habit of dropping a suffixed vowel if it comes right after another vowel.)
The important thing to remember is that in ergative constructions, we mark the Agent of the action by the .e suffix.
[Thomsen §173, Edzard §5.4.2.2]