Fortress Louisbourg Stamps - No Denomination

I can answer this one. These stamps have no explicit value because there was an anticipated rate change that would take effect prior to these stamps being released. Because changes in postal rates have to go through Parliament, the folks at Canada Post could not anticipate if legislators would approve the new rate they wanted. In order to avoid printing stamps with a postal rate that might not exist, they chose to leave those two issues undenominated and valid only for domestic postage. In the end, I believe the rate changed to 45 cents & Canada Post was looking for more (like 47 or thereabouts).
This happened previously in 1980 or 1981 & resulted in the release of the 'A' stamp. The rate for a domestic letter went from 17 cents to 30 cents. There was no predicting what the rate would be after Parliament finished hashing it out.

thank you winkerbids.