The IEEE patent policy is available at:
http://standards.ieee.org/guides/bylaws/sect6-7.html#6
The policy permits the use of patents with license fees in IEEE standards.
I'm not aware of any patents with royalties covering the MIDI format.
The W3C patent policy is far more friendly: "In order to promote the widest adoption
of Web standards ... W3C will not approve a Recommendation if it is aware that Essential
Claims exist which are not available on Royalty-Free terms". But that still allows
non-essential itmes to require royalties. The full policy is at:
http://www.w3.org/Consortium/Patent-Policy-20040205/
Sadly, the US and Japanese software patent laws are poisoning the creative commons for the
rest of the world.