Why does Mac OS X store individual font styles separately?

While Mac OS 9 used to permit you to store multiple fonts in a single suitcase , Mac OS X stores each font style in its own individual suitcase.

The old suitcase approach had inherent problems. It was very common for a single instance or font resource inside a font suitcase to become corrupt, making all the other faces in the suitcase unusable. To make matters worse, since users had the ability to open font suitcases, they could drag and drop to add, mix and remove font resources, formats and families in the same suitcase. This practice, though designed to make font management easier, often spawned more complex font problems.

Since entire suitcases are activated by font managers and a font can only be activated once, having the same fonts in multiple suitcases meant only one suitcase could be activated at a time. This often resulted in aggravating error messages.

Another complication of having multiple fonts in one suitcase arose when sending fonts to print service bureaus. If a suitcase contained more fonts than used in the document, the service bureau would need to figure out why they were supplied.

Also, there was no mechanism to search for fonts within suitcases. This made it especially difficult to resolve multiple, duplicate, corrupt and unmatched fonts.

Since the operating system activates suitcases, by isolating individual font styles, Mac OS X makes it possible for you activate just the fonts you and your applications require.