Slim Fat Applications removes extra code from an application that may not be necessary for use on your Mac.  See the Questions & Answers section below for more information.

To start, click the Slim Fat Applications… button on the main Yank window.  The following window appears.

 














In this example, we've selected a copy of Yank.  The next window shows the potential disk savings if you slim the application.  It's always recommended to check “Duplicate application first” before continuing, just in case this process does not correctly work.

 














If the operation was successful, the window below displays.  To verify all went well, check “Launch application” so that when you click OK, the application will start.
 










 
Questions & Answers for slimming a Fat application.

Q) What is a FAT application?

A) A FAT application is an application that can run in native mode on either a 68000 Mac (also called a 68K Mac) or a PowerPC Mac (also called a PPC Mac).  The application contains native code for both types of machines.  However, if you always only use a 68000 Mac or always only use a Power PC Mac, you don't need the code for the other type of Mac.  If you have a 68000 Mac (MacPlus, MacSE, Mac IIFX, etc), you don't need the PowerPC Mac code.  If you have a PowerPC Mac (any of the Macs sold today), you don't need the 68000 Mac code. 


Q) Where is the code kept on a FAT application?

A) Normally, for a PowerPC Mac, it's kept in the application's data fork.  There is also a  'cfrg' resource that resides in the resource fork.  Normally, for the 68000 Mac, the code is kept in the application's resource fork as a 'CODE' resource.   You need a special developer's application to access the data fork (such as Resorcerer), but you can view resources using ResEdit.


Q) What does Yank do when it slims an application?

A) To make a 68K application, Yank removes the data fork and the  'cfrg'  resource.  To make a PPC application, Yank removes all the 'CODE' resources.


Q) Is it safe to use Yank to slim an application?

A) Normally, yes.  HOWEVER, it's best to always make a backup of the application first.  Yank can do this for you, or you can make a backup using the Finder's Duplicate command under the File menu.  Once Yank slims the application, double-click on it to see if all is well.  If the slimmed application doesn't work or crashes your Mac, immediately drag the slimmed application to the Trash and use the backup.


Q) When is it not safe to use Yank to slim an application?

A) If the disk savings are small.  For example, if Yank reports a disk savings of less than 50K, especially for a large application, it's not recommended to slim the application.