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### 2.2 Undo and Backups

Viper provides multiple undo. The number of undo's and the size is limited by the machine. The Viper command `u` does an undo. Undo can be repeated by typing `.` (a period). Another `u` will undo the undo, and further `.` will repeat it. Typing `u` does the first undo, and changes the direction.

Since the undo size is limited, Viper can create backup files and auto-save files. It will normally do this automatically. It is possible to have numbered backups, etc. For details, see Backup and Auto-Save

The results of the 9 previous changes are available in the 9 numeric registers, as in Vi. The extra goody is the ability to view these registers, in addition to being able to access them through `p` and `M-y` (See Insert State, for details.) The Viper command `] register` will display the contents of any register, numeric or alphabetical. The related command `[ textmarker` will show the text around the textmarker. ‘`register`’ and ‘`textmarker`’ can be any letters from a through z.