Windows has a maximum PATH length of 260 characters, so that includes
the drive letter (+ colon and backslash) folder and sub-folder names and
Under Windows using the NTFS file system file and folder names may be up
to 256 characters long.
The following characters are invalid as file or folder names on Windows
/ ? < > \ : * | " and any character you can type with the Ctrl key.
In addition to the above illegal characters the caret ^ is also not
permitted under Windows Operating Systems using the FAT file system.
In addition to these characters, the following conventions are also illegal:
Placing a space at the end of the name
Placing a period at the end of the name
The following file names are also reserved under Windows:
com1, com2, com3, com4, com5, com6, com7, com8, com9, lpt1, lpt2,
lpt3, lpt4, lpt5, lpt6, lpt7, lpt8, lpt9, con, nul, and prn
MACINTOSH OS 9 CONVENTIONS
The only illegal character for file and folder names in Mac OS 9 is the
File and folder names may be up to 31 characters in length
MACINTOSH OS X CONVENTIONS
Since Mac OS X is build on top of UNIX there are a few inherent
conventions that OS 9 users may not expect. Because of this, migrating
certain files and folders from OS 9 to OS X may cause unexpected behavior.
The only illegal character for file and folder names in Mac OS X is the
File and folder names are not permitted to begin with a dot "."
File and folder names may be up to 151 characters in length
A file name can be up to 255 characters long. This restriction is a
file name restriction not a path name length restriction.
A file name can contain any character at all with the exception of
slash ("/") which is used as a path name component separator and NUL (a
character with all bits set to zero) which is used internally as a file
name terminator. Thus a file name could consist entirely of space and
back space characters.
All characters are significant. In other words the Unix file naming
system is case sensitive. Lower case file names are more common than
upper case file names.
File names do not have components or extensions. You can have as many
dots as you like (up to 255 !) in a Unix file name. Many applications,
however, regard the part of a file name after the last dot as having
As any freshly created directory will contain entries "." and ".." (dot and
dot-dot referring to the current directory and the parent directory,
files cannot be named "." and ".."
All filenames in URI's should conform to RFC 1630 (no spaces, necessary to escape characters etc.)