Module talk:Canada NTS
maps of water
why? series 121, 341, 561, 780, 781, 910, may exist at https://maps.canada.ca/czs/index-en.html when the National Tiling System grid coverage is turned on (911 doesn't appear to exist there) but all that is within those grids is a lot of cold cold water. Why bother with that in this module? Does the mapping shift to nautical charts for those regions? And what about the other series omitted from File:NTS Zones and Map Series Numbers.png (0, 4–9, 17–19, 28, 50, 51, 60, 61, 70, 71, 80, 81, 90, 91, 100, 101, 108, 109, 118, 119)? Presumably there are no maps for those series; if there were, wouldn't series 0, 4–9, 17–19 etc NTS map sheet names be in Module:Canada NTS/data?
I've written a more strict lat/lon validator that returns false when lat/lon are outside the bounds of the grid overlay in File:NTS Zones and Map Series Numbers.png. The validator prevents grid() from calculating NTS IDs for points outside of the overlay by returning early with an error message. Using that validator means that for points in series 121, 341, 561, 780, 781, 910 (and 911 if it exists), grid() will return an error message so there is no need to accommodate those series within grid().