feature

feature n.  1. A good property or behavior (as of a
   program).  Whether it was intended or not is immaterial.  2. An
   intended property or behavior (as of a program).  Whether it is
   good or not is immaterial (but if bad, it is also a
   {misfeature}).  3. A surprising property or behavior; in
   particular, one that is purposely inconsistent because it works
   better that way -- such an inconsistency is therefore a
   {feature} and not a {bug}.  This kind of feature is sometimes
   called a {miswart}; see that entry for a classic example.  4. A
   property or behavior that is gratuitous or unnecessary, though
   perhaps also impressive or cute.  For example, one feature of
   Common LISP's `format' function is the ability to print
   numbers in two different Roman-numeral formats (see {bells,
   whistles, and gongs}).  5. A property or behavior that was put in
   to help someone else but that happens to be in your way.  6. A bug
   that has been documented.  To call something a feature sometimes
   means the author of the program did not consider the particular
   case, and that the program responded in a way that was unexpected
   but not strictly incorrect.  A standard joke is that a bug can be
   turned into a {feature} simply by documenting it (then
   theoretically no one can complain about it because it's in the
   manual), or even by simply declaring it to be good.  "That's not a
   bug, that's a feature!" is a common catchphrase.  See also
   {feetch feetch}, {creeping featurism}, {wart}, {green
   lightning}.

   The relationship among bugs, features, misfeatures, warts, and
   miswarts might be clarified by the following hypothetical exchange
   between two hackers on an airliner:

   A: "This seat doesn't recline."

   B: "That's not a bug, that's a feature.  There is an emergency
   exit door built around the window behind you, and the route has to
   be kept clear."

   A: "Oh.  Then it's a misfeature; they should have increased the
   spacing between rows here."

   B: "Yes.  But if they'd increased spacing in only one section it
   would have been a wart -- they would've had to make
   nonstandard-length ceiling panels to fit over the displaced
   seats."

   A: "A miswart, actually.  If they increased spacing throughout
   they'd lose several rows and a chunk out of the profit margin.  So
   unequal spacing would actually be the Right Thing."

   B: "Indeed."

   `Undocumented feature' is a common, allegedly humorous euphemism
   for a {bug}.