I suppose it is because the colon is used for NTFS alternate data streams, see the example in the introduction here: https://docs.microsoft.com/en-us/sysinternals/downloads/stre...

Wonder if NTFS 'lets' you. I know the API does not let it. But I wonder if you could get it in a different way. I know you can sneak case sensitivity in here and there.

Think I shall go ruin a VM tonight... :)

Had a hell of a time downloading a torrent with a colon in the name.