Locked and read-only source documents can be brought into the ad hoc Document Separation window, but these locked documents can not be edited in the same fashion as unlocked documents are. Pages dragged out of a locked document will be copied to their destination. The original source document will remain intact and unchanged within the Document Separation layout. Pages cannot be dragged into a locked document.
If attempting to append an unlocked document to a locked document by performing a Partition/Append task on the last page of the locked document, the unlocked document's pages will not be moved into the locked document.
In Document Display Mode, locked documents are labeled with a lock icon in the Document Header:
Hovering over this icon will display who holds the lock on this document.
In Page Display Mode, pages of locked documents are bordered in black and display a lock icon in the corner: