 These four-character codes were designed to specify both the application that created the file (the creator code) and the specific type of the file (the type code) so that other applications could easily open and process the file data.However, while type and creator codes extended the flexibility of the system — a particular type of file was not restricted to opening in a particular application — they suffered many of the same problems as file extensions.Type and creator codes could be lost when files were transferred across non-Macintosh systems (such as Unix-based servers), and the plethora of type codes made identification problematic.