|Warning:||The item System file is essential system software. Do not attempt to remove it; your Mac may no longer start up without it.|
The System file before System 7
Before System 7, the System file just lay on the root level of the System Folder. It could not be opened by the user.
The System file in and after System 7
With the release of System 7, the System file became a suitcase. The following items could be dropped onto the System file (or be rerouted to the System file if it was dropped on a closed System Folder icon in Mac OS 8 through Mac OS 9):
The System file in Mac OS X
The System file in Mac OS X was relocated to System > Library > CoreServices, and is no longer openable. A double-click will result in the error dialogue box, stating "Item "System" is used by Mac OS X and cannot be opened".
The System file in list views
In Mac OS X, the System file appears in list views as a document icon with the upper-right hand corner folded down.
Before Mac OS X, however, the System file appeared in list views as a document icon with the upper-left hand corner folded down.