Creator code

A creator code is a mechanism used in pre-OS X versions of the Macintosh operating system to link a data file to the application program which created it, in a manner similar to file extensions in other operating systems. Codes are limited to four characters. For example, the creator code of the HyperCard application and its associated "stacks" is WILD. This allows the application to launch and open a file whenever any of its associated files is double-clicked.

Creator codes are not readily accessible for users to manipulate, although they can be changed with certain software tools.