What is "dreimorengesetz"

The so-called three-mora rule is a linguistic rule which argues that an enclitic cannot be more than three moras in length. That is, three shorts, a long and a short, or a short and a long. Within a single word the most that can follow the accent is a long and a short.

Dreimorengesetz is a German term which translates to "three- mora rule." This name is given to the rule of Hermann Hirt (1865–1936) for placing the accent in a Germanic text.