Creator code

The creator code is responsible for linking the file and the program that will launch when the file is double-clicked. This Mac OS window show four files of the same type code (MP3), but with four different creator codes: Audn (Audion), hook (iTunes), SCPL (SoundApp) and NSWa (Winamp).

A creator code is a mechanism introduced in pre-Mac 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 four-byte OSTypes. 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.

The binding are stored inside the resource fork as BNDL and fref resources. These resources maintained the creator code as well as the association with each type code and icon.

Creator codes could contain numbers and some special characters. Occasionally they represented inside jokes. For instance, the Marathon computer game had a creator code of 26.2 (the approximate length, in miles, of a marathon) and Marathon 2: Durandal had a creator code of 52.4.

The key difference between extensions and Apple's system is that file type and file ownership bindings are kept fully distinct. This allows files to be written of the same type - TEXT say - by different applications, and freely opened by any application that can read TEXT files, but when double-clicked, will open the original application that created it. With the extensions approach, this distinction is lost - all files with a .txt extension will be mapped to a single text editing application.

Mac OS X retains creator codes, but supports extensions as well (However, beginning with OS X 10.6 Snow Leopard, creator codes are ignored by the Operating System.). Creator codes have been internally superseded by Apple's Uniform Type Identifier scheme, which manages application and file type identification as well as type codes, creator codes and file extensions.

Apple's developer documentation states that applications should continue to set type codes and optionally set creator codes. If either already exists, applications should preserve them.^[1] Furthermore, creator codes are used in document binding prior to the file extension alone.^[2]

Creator codes are not readily accessible for users to manipulate, although they can be viewed and changed with certain software, most notably the Mac OS X command line tools GetFileInfo and SetFile which are installed as part of the developer tools into /Developer/Tools.

References

1. ^ "File System Overview: Filename Extensions". Developer.apple.com. 2009-08-14. http://developer.apple.com/documentation/MacOSX/Conceptual/BPFileSystem/Articles/FilenameExtensions.html#//apple_ref/doc/uid/20002297-110671. Retrieved 2010-05-30. 
2. ^ [1]^{[dead link]}

See also

• Type code
• Uniform Type Identifier

External links

• The Type/Creator Database Website
• Apple's web page for reserving Creator codes (so that every application gets a unique code)
• How application binding policy changed in Snow Leopard