These types of fares have been around for quite some time. I believe that this particular farebasis came about about the same time as AC rolled out it's new one way economy fare pricing structure over a year ago. In any case, it's just a new name for an old fare type. The one thing to note is that there are no enroute stopovers permitted with this one.
And, for the cibc promo, booking class is C for all business fares. And also yes, this fare is useable as it seems that AC has finally gotten the drift (at least on this) and is permitting even YE9 type fares to be used (used to be you couldn't even use a YR or a Y2) on the economy end of the promo.