macOS post 10.7 also has the "Locked" file attribute; and optionally auto-applies "Locked" to documents after a set interval. "Locked" files behave similar to

macOS post 10.7 also has the "Locked" file attribute; and optionally auto-applies "Locked" to documents after a set interval. "Locked" files behave similar to "Stationery Pad" files, though with slight differences in workflow. You can open a "Locked" document, but when you attempt to make any changes to it, the program will pop a modal informing you that the document is "Locked", and asking whether you want to 1. unlock the document (and then apply your attempted change to the original); 2. duplicate the document (and then apply your attempted change to the duplicate); or 3. cancel your attempted change. "Locked" documents entirely subsume/obsolete "Stationery Pad" documents, IMHO. Locking gives you all the benefits of edits triggering a duplication of the document; while also offering you the option to edit the original if you so desire (without needing to close out of the document and modify its attributes first); and without creating unnecessary duplicates when all you wanted to do was view the document.