Here an initial music theory breakdown by time, frequency and dynamics in the form of a Venn Diagram, and which might conceivably form the basis of a music theory classification tree. It is also suggestive of further subdivisions dedicated to (say) orchestration and/or performance.
Though it clearly arose out of practical considerations, for it to be of practical use in future applications, a Dewey-Decimal hierarchy would need to be imposed.
ASIDE: happily, this hierarchy specifically avoids those physical configuration attributes MISSING from the Hornbostel-Sachs instrument classification system, such as number of notes per octave, temperament or intonation, scale length, tuning etc. (With many instruments across multiple cultures sharing similar characteristics, these physical qualities need appended to the HS system to arrive at a comprehensive, if -even then- not quite "name-unique" instrument definition. Here, due to the layering of components from, for example base board through to string / key or other interface element, the order of Dewey-Decimal indexing is critical).
Source: The Conductor Program