The Natural Resources Canada topographic map A 741, 83 C/7, edition 3 has a (bilingual) indication at the bottom stating:
WEST OF FIFTH MERIDIAN OUEST DU CINQIÈME MÉRIDIEN
What does this mean? It's around 117°W, so it is indeed west of the 5th meridian, but I think something else is meant here. Does this have a specific meaning on a topographic map?