"since many other railway:position's use decimal numbers, I'm apprehending .0 here to clarify that those mileposts haven't."

This is comparable to tagging `foot=no` on `highway=motorway`. Motorways imply `foot=no`, so it's unnecessary to add the `foot` tag unless the value is something other than `no`. Motorways with `foot=yes` are an exception; railroad mileposts with trailing decimal zeroes are an even rarer exception.