There are Canadian stamps which have no denomination marked,
nor
P , nor A. Nothing.
Unitrade 1546 flag and 1547 - 1551 forts.
There was no value shown because
Canada Post was
asking for a rate increase.
But the politicians in Ottawa denied it.
Must have been an election year.
Therefore the printer was instructed to leave off the
value and they were sold as 43c stamps.
I always thought that theoretically these
could be used anytime as first class postage
jut like the P stamps.