For a thorough understanding of MIDI technology, please view all of the documents that are listed on the Complete MIDI 1.0 Detailed Specification page and in the Specs section of this website. This includes the new MIDI Polyphonic Expression (MPE) Specification, and the new Capability Inquiry Messages, both of which are available for download on the Complete MIDI 1.0 Detailed Specification page.
The Complete MIDI 1.0 Detailed Specification document captured the state of MIDI as of 1996. When combined with the numerous supplements and addenda to the MIDI Specifications which were made after 1996, this document is the basis for a thorough understanding of MIDI technology. (Use this link to download this document and all of the later supplements.)