doc string of execute-extended-command does not mention its argument

[Drew Adams]

The doc string of execute-extended-command should describe its
argument. What's needed is something like this, from the Elisp manual:

     If the command asks for a prefix argument, it receives the value
     PREFIX-ARGUMENT.  If `execute-extended-command' is called
     interactively, the current raw prefix argument is used for
     PREFIX-ARGUMENT, and thus passed on to whatever command is run.

It is important for users using `C-h f execute-extended-command' to
get some explanation of the argument.

Also (a minor detail), the example in the Elisp manual is a particular
case, and can be misleading. It uses an argument value of 1, and shows
the `1' appearing in the prompt. But this is only the behavior with an
explicit argument; it is not what you see when you do just `M-x',
which gets an implicit arg of `1'.  In that case, the `1' does not
appear in the prompt. It would be better for the Elisp example to use
another number, say, 2, because that represents the more general
case. An added detail would be to perhaps mention that in the case of
1 the value is only displayed when...


In GNU Emacs 22.0.50.1 (i386-mingw-nt5.1.2600)
 of 2006-03-20 on W2ONE
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