Versions and Autosave have been part of OS X since 2011, and Apple thinks these features are so intuitive they don't need explanation. For those who disagree, we created a lengthy explanation.
Here are the big ideas:
•As you work, your file is automatically saved. You don't have to think about saving. Close a project file when you are done working with it. Open it when you want to work on it again.
•When you quit Prism, it remembers the files that were open. When you next launch Prism, those files will open again. This means you won't see Prism's Welcome dialog unless you closed all open files before quitting.
•If you need to, you can revert a file back to how it was an hour (or a day...) ago.
•The File..Save command has a new purpose after its first use to specify a file name and location. After that, use the Save command to save a milestone you can revert to.
•The File..Save As command is gone, replaced with three new commands: Rename, Duplicate and Move. Whatever your goal with Save..As is probably done better with one of these three commands.
•Two settings in the General tab of Systems preferences affect how your work flows: whether to keep changes when closing a document, and whether to open the documents you were working on when you start an application. These apply to all applications that use the new way of working, not just Prism. We suggest you keep both options checked.