http://www.tc.gc.ca/civilaviation/gener ... /spins.htm
So according to TC (the legal definition don't you knowTypes Of Spins
1. An incipient spin is that portion of a spin from the time the aeroplane stalls and rotation starts, until the spin becomes fully developed. An incipient spin that is not allowed to develop into a fully developed spin is commonly used as an introduction to spin training and spin recovery techniques.
2. A fully developed spin occurs when the aircraft angular rotation rates, airspeed, and vertical speed are stabilized from turn-to-turn in a flight path that is close to vertical.
3. A flat spin is characterized by a near level pitch and roll attitude with the spin axis near the C of G of the aeroplane. Recovery from a flat spin may be extremely difficult and, in some cases, impossible.

So I would have to disagree with that 180 degree rule. It seemed pretty straight forward to me, though it is quite possible that TC has some other cryptic rule burried in the heap somewhere that contradict this definition.
I would be interested to see what you were looking at to define that 180 degree mark.