AppleSingle

AppleSingle is one of the systems used to store the Resource Fork of Macintosh files on filesystems not natively supporting it, something which became necessary when Apple moved to Unix-based operating systems instead of "classic" MacOS. AppleDouble is an alternative format to accomplish the same end, using two files where AppleSingle uses one.

AppleSingle combines the data and resource forks with Finder meta-information into a single file, similar in concept to MacBinary.

Format detail links

 * File format details
 * RFC 1740 (describes various Mac-specific formats)

Utilities

 * Mac Binary Converter
 * Mac::AppleSingleDouble Perl library

Other links

 * Wikipedia article
 * MacBinary and Binhex 4.0 considered harmful