It is advised to save a work regularly. Indeed, a bug or an ill-conceived program can cause a crash or stuck OM in endless iterations, in which case you will have to force the application to quit.
To save a patch
File / Save
Cmd
+ s
.To reload the last saved version of a patch :
File / Last Saved
,Ctrl
/ right click in the editor, choose Last Saved
.If a patch is used in another patch, OM doesn't create a copy. Its original reference in the workspace will be affected by subsequent modifications as well. To preserve the original item, one can resort to internal patches or duplicate it to preserve the original reference from possible modifications.