Instances of simple data types like strings or numbers can easily be compared and arranged on the basis of a lexical or numerical ordering system. Generic operations are available for the test of equality, greater-than- or less-than-relations can be generated and sometimes even similarity can be assessed. But how to handle multimedia data types such as music? Can we compare music at all? Despite many achievements in music information retrieval and besides low-level evaluation of spectral features we are not able to compare music in their entirety. Therefore we propose a semantic indexing method for musical documents that is based on a generic music description form and which delivers the foundation for comparison and partial ordering music.