bug#21754: 25.0.50; doc of `grep' - no description of how to call it: COMMAND-ARGS undefined

[Drew Adams <drew.adams@oracle.com>]

Here is the entire doc string:

  (grep COMMAND-ARGS)

  Run grep, with user-specified args, and collect output in a buffer.
  While grep runs asynchronously, you can use C-x ` (M-x next-error),
  or RET in the *grep* buffer, to go to the lines where grep found
  matches.  To kill the grep job before it finishes, type C-c C-k.

  For doing a recursive 'grep', see the 'rgrep' command.  For running
  'grep' in a specific directory, see 'lgrep'.

  This command uses a special history list for its COMMAND-ARGS, so you
  can easily repeat a grep command.

  A prefix argument says to default the argument based upon the current
  tag the cursor is over, substituting it into the last grep command
  in the grep command history (or into 'grep-command' if that history
  list is empty).

There is _zero_ information here about parameter COMMAND-ARGS.
The Emacs and Elisp manuals offer no more help.

How is a user expected to call this function from Lisp?
Doc strings should _fully specify_ a function's parameters.


In GNU Emacs 25.0.50.1 (i686-pc-mingw32)
 of 2015-10-09
Bzr revision: af45926d66d303fdc4c2c3ebbc820b4a54d9e4a0
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --host=i686-pc-mingw32 --enable-checking=yes,glyphs'