What are invalid characters for a file name under OS X?

I am having trouble finding this information, and trial and error is telling me that there may not be any. What are invalid characters for a file name on OS X Lion (10.7)?

HFS Plus allows "Unicode, any character, including NUL. OS APIs may limit some characters for legacy reasons"

What are invalid characters for a file name under OS X?

wiki HFS+:

Allowed characters in filenames Unicode, any character, including NUL. OS APIs may limit some characters for legacy reasons

Finder doesn't currently allow entering colons in in file names, but it does allow entering backslashes. However the characters shown as slashes in Finder are shown as colons in shells, and vice versa. Finder doesn't allow any ASCII control characters either.

Bash seemed to allow all control characters except \000 (NUL). I tested it by running the output from:

for i in {1..31} 127 0; do echo touch \\$(bc <<< "obase=8;$i"); done