(The questions and answers about "IPv5" are sort of funny.)
Quite whatever happened to that?
It is funny that the DoD wouldn't know, since they actually deployed it.
The code point 5 was used to differentiate packets belonging to the
"stream" service parallel to IP, ST-II (RFC 1190). It was used to carry
video conferences services. I remember taking part to one such
conference in a DARPA locale.
-- Christian Huitema