The document discusses various musical coding systems used for notation, data management, and analysis. It describes MIDI (Musical Instrument Digital Interface) as a protocol for communication between keyboards and synthesizers. It also describes DARMS (Digital Alternate Representation of Musical Scores), a musical notation code developed in 1963, and Humdrum, a coding system for storage and analysis of musical data. Both DARMS and Humdrum allow for coding of various musical parameters like clefs, key signatures, time signatures, pitch, duration, and more.