Type and creator codes are four-character codes used by the Finder to identify files and applications.
The type code identifies the type of file and is used by applications to determine if they can open a given file. Each file type has a unique format and can usually only be opened by a single application. A few “universal” file types exist that many applications recognize. These include “TEXT” files, which most word processors can open, “PICT” files, which many graphics programs can open, and “APPL” files, which are applications that the Finder can launch. You should change type codes only in special instances, otherwise an application may try to read the file incorrectly.
The creator code identifies the application that created the file. The Finder uses creator codes to choose the correct icon for a file, and also to launch the correct application if you double-click a file. You can change the creator code to “trick” the Finder into thinking that a file has been created using another application. The Finder will then show that new application’s icon for the file and launch that new application if you double-click the file. If you do this, make sure the file is a type that the new application recognizes.
Changing types and creators and the other Finder attributes with FileTyper is potentially dangerous. As a rule, alter these attributes only if you positively know what you’re doing.
One question that is often asked is, does there exist a complete list of all type and creator codes? The answer is, yes, but it is maintained internally by Apple Computer, and they will not release it to the public. There are some lists maintained privately by individuals, posted to ftp sites, file servers or discussion groups periodically. Some of these are excellent resources, but none are complete and they’re not guaranteed to be accurate.
