The terms “grand rights” and “small rights” refer to specific usages of musical works for the stage. A distinction is made between dramatic and non-dramatic or concert performances of a work: in the latter case, one speaks of a “small right,” whereas in the case of a dramatic performance of the choreographed work, one speaks of a “grand right.”
These terms are not found in copyright law. The German Music Publishers’ Association, the German Theatre Association, and the public service broadcasters have established existing regulations that are not necessarily binding in the form of a set of rules. Creators or their stage publishers are responsible for the exploitation of “grand rights,” while collecting societies are responsible for the exploitation of “small rights.”
Source: Wikipedia, edited (only available in German)