Indeed I had never relied on that behaviour myself, but on quite about every filesystem I had seen thus far would readdir return qw/. ../ as the first two entries, and yet I had never ever seen this described as a requirement, so I had always wondered if by any chance it were - except undocumented or documented in some arcane place: now we have at least one bit of experimental evidence it actually isn't. (Of course I'm not claiming to be a fs expert or let alone knowledgeable person, in which case I would have known better to start with...)