[M4IF Technotes] Why no MPEG-5, 6, 8, etcetera

[Ben Waggoner]

Folks,
    Not a deep question, I'd guess, but does anyone have any insight into
how MPEG version numbers are chosen.  MPEG-1 and -2 make sense, and I know
-3 was going to be the HD spec, which was instead rolled back into -2.  And
then we have -4.  But why the big jumps then to -7 and -21?  Were there a
bunch of proposals out there that didn't go anywhere, or are still in
progress?  Was room left for additional intermediate versions (ala the US
Bankruptcy code, which originally only had odd numbered chapters)?
Ben Waggoner
Interframe Media <http://www.interframemedia.com>
Digital Video Compression Consulting, Training, and Encoding