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      Node("M-X")

      Chapter[Extended (Meta-X) Commands and Functions]

       Not  all NMODE commands are of the one or two character variety
     you have seen so  far.    Most  commands  have  long  invocations
     composed  of  English  words.   This is for two reasons: the long
     invocations are easier to remember and more suggestive, and there
     are not enough two-character combinations for  every  command  to
     have one.

       The  commands  with  long  names  are  known  as   dfn[extended
     commands] because they extend the set of two-character commands.

      Section[Issuing Extended Commands]

      DoubleWideCommands[ M-X        Begin   an   extended    command.
     Follow  by  the command invocation only; the command will ask for
     any arguments.

     C-M-X   Begin  an  extended  command.    Follow  by  the  command
     invocation only; the command will ask for any arguments.  ]

      index{extended
     commands} index{M-X} index{functions} index{commands}
       Extended  commands  are also called  dfn[M-X commands], because
     they all start with the character Meta-X (fnc{m-x-prefix}).   The
     M-X  is  followed  by  the command's long, suggestive invocation.
     Terminate the invocation with a  Return3{}.  For example,  Meta-X
     Auto     Fill     Mode return2{}     invokes     the     function
     auto-fill-mode-command.  This function when executed  turns  Auto
     Fill mode on or off.

       There  are  a  great  many  functions in NMODE for you to call.
     They will be described elsewhere in the manual, according to what
     they do.  Here we are concerned only with  extended  commands  in
     general.

      SubSection[Typing The Command Name]

      index{Backspace} index{C-D} index{C-U} index{C-G} index{echo
     area}
       When  you  type  M-X, the cursor moves down to the echo area at
     the bottom of the screen.  "M-X" is printed there, and  when  you
     type  the  command  name  it  echoes  there.    This  is known as
      dfn[reading a line in the echo area].  You can use any moving or
     deleting command (C-A, C-E, C-F, C-B , C-D, Backspace, etc.)   to
     help  construct  the  M-X  command.  A C-G cancels the whole M-X.
     These editing characters apply any time NMODE reads a line in the
     echo area, not just within M-X.
                                   - 2 -


      index{prompting} index{TECO} index{Read Command Prompt}
       The  string  "M-X"  which  appears in the echo area is called a
      dfn[prompt].  The prompt always tells you what sort of  argument
     is required and what it is going to be used for; "M-X" means that
     you are inside of the command M-X, and should type the invocation
     of a function to be called.

      SubSection[Completion]

      index{command completion} index{Altmode} index{Space}
       You  can  abbreviate  the  name of the command, typing only the
     beginning of the name, as much  as  is  needed  to  identify  the
     command  unambiguously.    You  can  also  use  completion on the
     function name.  This means that you  type  part  of  the  command
     name,  and  NMODE visibly fills in the rest, or as much as can be
     determined from the part you have typed.

       You request completion by typing  Return3{}.  For  example,  if
     you  type   W[M-X Au Return2{}, the "Au" expands to  W["Auto Fill
     Mode"] because "Auto Fill Mode" is the  only  command  invocation
     that  starts with "Au".  If you ask for completion when there are
     several alternatives for the next character, the bell  rings  and
     nothing else happens.

       Space  is  another  way to request completion, but it completes
     only one word.  Successive Spaces complete one word  each,  until
     either there are multiple possibilities or the end of the name is
     reached.   If  the  first  word of a command is Edit, List, Kill,
     View or What, it is sufficient to type just the first letter  and
     complete  it  with a Space.  (This does not follow from the usual
     definition of completion, since the single letter  is  ambiguous;
     it is a special feature added because these words are so common).

      INFO{   Note("MMArcana"  "MM"), for more information on this and
     other topics related to how extended commands work, how they  are
     really the foundation of everything in NMODE, and how they relate
     to customization.}

      Node("MMArcana")

      Section[Arcane Information about M-X Commands]  index{M-X}

       You  can  skip  this  section  if  you  are  not  interested in
     customization, unless you want to know what is  going  on  behind
     the scenes.

      index{customization} index{Connected} index{Functions}
       Actually,   xxi[every] command in NMODE simply runs a function.
     For example, when you type the command C-N, it runs the  function
     " fnc{move-down-extending-command}"  C-N  can  be thought of as a
     sort of abbreviation.  We say  that  the  command  C-N  has  been
                                   - 3 -


      dfn[connected]             to            the            function
      fnc{move-down-extending-command}.  The name is  looked  up  once
     when  the command and function are connected, so that it does not
     have to be looked up again each time the command is  used.    The
     documentation  for  individual  NMODE  commands usually gives the
     name of the function  which  really  implements  the  command  in
     parentheses after the command itself.

      index{Set Key}
       Just as any function can be called directly with M-X, so almost
     any  function  can  be  connected  to a command.  You can use the
     function Set Key to do this.  Set  Key  takes  the  name  of  the
     function  as  a string argument, then reads the character command
     (including metizers or other prefix characters) directly from the
     terminal. To  define  C-N,  you  could  type   example[  M-X  Set
     Key Return1{}move-down-extending-command Return1{}   ]  and  then
     type C-N.  If you use the function View  File  often,  you  could
     connect  it  to  the  command  C-X Z (not normally defined).  You
     could even connect  it  to  the  command  C-M-V,  replacing  that
     command's  normal  definition.    Set  Key is good for redefining
     commands in the middle of editing.  An init file or  EVARS() file
     can do it each time you run NMODE.   Note("Init").

      Subsection[Subroutines]

      index{subroutines}  index{command completion}
       NMODE is composed of a large number of functions, each  with  a
     name.   Some  of  these functions are connected to commands; some
     are there for you to call with M-X;  some  are  called  by  other
     functions.  The last group are called subroutines.
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