<VV> 60-64 Corvair does not have IRS?

[Ramon Rodriguez III]

This is something I've been wondering for a while but haven't asked about.
 I ran across a trivia point that the first year for IRS on Corvairs was
1965.  There was a not stating that the EM suspension was only semi-IRS.

I don't see why the swing axle suspension would not be considered true IRS.
 Is this just a matter of terminology or is the EM suspension truly not
fully independent in some sense?

Thanks!

Ray R.