The AUTODELETE and UPDATE directives (also available from Command Mode) are similar to the "d/VUE" directives of the same names. The both relate to an optional feature in which an automatic update notation is added to the top of the file whenever you finish out of it. The notation looks something like this:
!*! Updated on 02-Oct-98 at 06:33 PM by Jack; edit time: 0:45:23
Appropriate default comment markers ("!*!", "/*" and "*/", or ";*;") are determined on the basis of the file extension. If the file extension is not recognized, the feature is turned off. If you prefer to define your own comment markers, then use the UPDATE = <sc>{,<ec>} syntax (where <sc> is the "start comment" sequence and <ec> is the optional "end comment" sequence).
When the UPDATE feature is active, AUTODELETE may come in handy to automatically remove older entries (so you do not accumulate an infinite number of them or have to manually remove them). Setting it to ON results in just the last entry being preserved. If you specify a number instead, it will save that many entries before deleting older ones. See the notes on Special Commands for information about the related ^SE and ^_E commands.