| BUNDLE_EXTENSION | |
| ---------------- | |
| The file extension used to name a :prop_tgt:`BUNDLE`, a :prop_tgt:`FRAMEWORK`, | |
| or a :prop_tgt:`MACOSX_BUNDLE` target on the OS X and iOS. | |
| The default value is ``bundle``, ``framework``, or ``app`` for the respective | |
| target types. |