The IMF family of standards is developed by Technology Committee 35PM of the Society of Motion Picture and Television Engineers.
While published SMPTE specifications are available publicly, access to draft specifications and the ability to contribute directly to the development process is limited to members of the SMPTE Standards Community. See the FAQ.
Anyone can become a member of the SMPTE Standards Community by signing-up. Once signed-up, Technology Committee 35PM can be joined through its home page.