On old Macs before OS X files already could have two "forks" - a data fork and a resource fork.
According to Wikipedia, at some point the HFS+ filesystem of OS X gained the ability to have an arbitrary number of forks, much like Microsofts "Alternate Data Streams" (
HFS Plus permits filenames up to 255 UTF-16 characters in length, and n-forked files similar to NTFS, though until recently, almost no systems software takes advantage of forks other than the data fork and resource fork.
I want to know what the official term is for these forks or streams. I guess it's possible they're just called "forks" but that terms has several meanings already in computing. I've done some searching but can't find a definitive answer.