directory order of files

[Edmund GRIMLEY EVANS <edmundo@rano.org>]

With Linux ext2, and some other systems, when you create files in a
new directory, the file system remembers their order:

$ mkdir new
$ cd new
$ touch one two three four
$ ls -U
one  two  three  four

(1) Is there any standard that says a system should behave this way?
Is there any software that depends on this behaviour?

(2) Are there Linux file systems that don't work this way? Maybe
someone with a mounted writable reiserfs could do a quick check.

Please copy replies to me as I am not subscribed. Thanks.

Edmund