Jason Sears asked a very interesting question regarding MacOS X and long file names. How are they supported? There is no information yet on Apple's site, but this is what I discovered with a little experimentation.

MacOS X supports long file names. Very long - up to 255 characters, but only the first 150 are visible on the desktop when an icon text box is selected. If you use the File Inspector (Get Info), you can scroll with the arrows to see an entire name.

When an icon is not selected, only the first 18 characters of a name are visible.

But what happens if you view that filename under MacOS 9? Only 31 characters are displayed and the truncated characters from MacOS X are converted to some form that eludes me.

Carsten Klapp sends this explanation:

The strange letters at the end of truncated long filenames from Mac OS X correspond to the file's or folder's reference number in the directory, converted to hexadecimal so that it uses up fewer filename characters. It's not pretty but it sure beats Windows 95's "MYDOCU~1.TXT".

This value was chosen to avoid any possibility of a duplicate filename resulting from truncating the long name. The reference number is guaranteed to be unique since each file or folder is assigned a unique number by the
filesystem when a file is created.

Note that HFS+ directly supports long filenames, it is the Finder itself and classic applications that cannot make use of the long filename feature of HFS+.

I have confirmed this myself by examining the folder reference number of a truncated folder name with Resorcerer. When I find any documentation from Apple about this I will send a link.