but then i realized i'm not likely to mount a remote M2dir so i'm far less concerned with the answer.
In that case, let me definitely take the time to provide you an answer then... :D
The linked blog post outlining the spec is slightly outdated/lagging behind the actual spec document here: https://man.sr.ht/~bitfehler/m2dir/
The updated detail relevant to your query being: the `:` separator was replaced by use of `,` (comma) as the separator instead: https://man.sr.ht/~bitfehler/m2dir/#parsing-filenames
More detail on the reasons for the change is given in the associated commit message [informative commit messages? what a novel concept! :D ]: https://git.sr.ht/~bitfehler/m2dir/commit/100b7683f53899c836... [TL;DR: bash & NTFS/ADS]
but then i realized i'm not likely to mount a remote M2dir so i'm far less concerned with the answer.