Merge branch 'master' into comment-cache

[emacs.git] / etc / refcards / refcard.tex

% Reference Card for GNU Emacs

% Copyright (C) 1987, 1993, 1996-1997, 2001-2017 Free Software
% Foundation, Inc.

% Author: Stephen Gildea <gildea@stop.mail-abuse.org>

% This document is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.

% As a special additional permission, you may distribute reference cards
% printed, or formatted for printing, with the notice "Released under
% the terms of the GNU General Public License version 3 or later"
% instead of the usual distributed-under-the-GNU-GPL notice, and without
% a copy of the GPL itself.

% This document is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
% GNU General Public License for more details.

% You should have received a copy of the GNU General Public License
% along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.


% This file is intended to be processed by plain TeX (TeX82).
%
% The final reference card has six columns, three on each side.
% This file can be used to produce it in any of three ways:
% 1 column per page
%    produces six separate pages, each of which needs to be reduced to 80%.
%    This gives the best resolution.
% 2 columns per page
%    produces three already-reduced pages.
%    You will still need to cut and paste.
% 3 columns per page
%    produces two pages which must be printed sideways to make a
%    ready-to-use 8.5 x 11 inch reference card.
%    For this you need a dvi device driver that can print sideways.
% Which mode to use is controlled by setting \columnsperpage.
%
% To compile and print this document:
% tex refcard.tex
% dvips -t landscape refcard.dvi
%
% Thanks to Paul Rubin, Bob Chassell, Len Tower, and Richard Mlynarik
% for their many good ideas.

%**start of header
\newcount\columnsperpage
\newcount\letterpaper

% This file can be printed with 1, 2, or 3 columns per page.
% Specify how many you want here.
\columnsperpage=3

% Set letterpaper to 0 for A4 paper, 1 for letter (US) paper.  Useful
% only when columnsperpage is 2 or 3.
\letterpaper=1

% PDF output layout.  0 for A4, 1 for letter (US), a `l' is added for
% a landscape layout.
\input pdflayout.sty
\pdflayout=(1l)

% Nothing else needs to be changed below this line.

\input emacsver.tex

\def\shortcopyrightnotice{\vskip 1ex plus 2 fill
  \centerline{\small \copyright\ \year\ Free Software Foundation, Inc.
  Permissions on back.}}

\def\copyrightnotice{
\vskip 1ex plus 2 fill\begingroup\small
\centerline{Copyright \copyright\ \year\ Free Software Foundation, Inc.}
\centerline{For GNU Emacs version \versionemacs}
\centerline{Designed by Stephen Gildea}

Released under the terms of the GNU General Public License version 3 or later.

For more Emacs documentation, and the \TeX{} source for this card,
see the Emacs distribution, or {\tt http://www.gnu.org/software/emacs}
\endgroup}

% make \bye not \outer so that the \def\bye in the \else clause below
% can be scanned without complaint.
\def\bye{\par\vfill\supereject\end}

\newdimen\intercolumnskip       %horizontal space between columns
\newbox\columna                 %boxes to hold columns already built
\newbox\columnb

\def\ncolumns{\the\columnsperpage}

\message{[\ncolumns\space
  column\if 1\ncolumns\else s\fi\space per page]}

\def\scaledmag#1{ scaled \magstep #1}

% This multi-way format was designed by Stephen Gildea October 1986.
% Note that the 1-column format is fontfamily-independent.
\if 1\ncolumns                  %one-column format uses normal size
  \hsize 4in
  \vsize 10in
  \voffset -.7in
  \font\titlefont=\fontname\tenbf \scaledmag3
  \font\headingfont=\fontname\tenbf \scaledmag2
  \font\smallfont=\fontname\sevenrm
  \font\smallsy=\fontname\sevensy

  \footline{\hss\folio}
  \def\makefootline{\baselineskip10pt\hsize6.5in\line{\the\footline}}
\else                           %2 or 3 columns uses prereduced size
  \hsize 3.2in
  \if 1\the\letterpaper
     \vsize 7.95in
  \else
     \vsize 7.65in
  \fi
  \hoffset -.75in
  \voffset -.745in
  \font\titlefont=cmbx10 \scaledmag2
  \font\headingfont=cmbx10 \scaledmag1
  \font\smallfont=cmr6
  \font\smallsy=cmsy6
  \font\eightrm=cmr8
  \font\eightbf=cmbx8
  \font\eightit=cmti8
  \font\eighttt=cmtt8
  \font\eightmi=cmmi8
  \font\eightsy=cmsy8
  \textfont0=\eightrm
  \textfont1=\eightmi
  \textfont2=\eightsy
  \def\rm{\eightrm}
  \def\bf{\eightbf}
  \def\it{\eightit}
  \def\tt{\eighttt}
  \if 1\the\letterpaper
     \normalbaselineskip=.8\normalbaselineskip
  \else
     \normalbaselineskip=.7\normalbaselineskip
  \fi
  \normallineskip=.8\normallineskip
  \normallineskiplimit=.8\normallineskiplimit
  \normalbaselines\rm           %make definitions take effect

  \if 2\ncolumns
    \let\maxcolumn=b
    \footline{\hss\rm\folio\hss}
    \def\makefootline{\vskip 2in \hsize=6.86in\line{\the\footline}}
  \else \if 3\ncolumns
    \let\maxcolumn=c
    \nopagenumbers
  \else
    \errhelp{You must set \columnsperpage equal to 1, 2, or 3.}
    \errmessage{Illegal number of columns per page}
  \fi\fi

  \intercolumnskip=.46in
  \def\abc{a}
  \output={%                    %see The TeXbook page 257
      % This next line is useful when designing the layout.
      %\immediate\write16{Column \folio\abc\space starts with \firstmark}
      \if \maxcolumn\abc \multicolumnformat \global\def\abc{a}
      \else\if a\abc
        \global\setbox\columna\columnbox \global\def\abc{b}
        %% in case we never use \columnb (two-column mode)
        \global\setbox\columnb\hbox to -\intercolumnskip{}
      \else
        \global\setbox\columnb\columnbox \global\def\abc{c}\fi\fi}
  \def\multicolumnformat{\shipout\vbox{\makeheadline
      \hbox{\box\columna\hskip\intercolumnskip
        \box\columnb\hskip\intercolumnskip\columnbox}
      \makefootline}\advancepageno}
  \def\columnbox{\leftline{\pagebody}}

  \def\bye{\par\vfill\supereject
    \if a\abc \else\null\vfill\eject\fi
    \if a\abc \else\null\vfill\eject\fi
    \end}
\fi

% we won't be using math mode much, so redefine some of the characters
% we might want to talk about
\catcode`\^=12
\catcode`\_=12

\chardef\\=`\\
\chardef\{=`\{
\chardef\}=`\}

\hyphenation{mini-buf-fer}

\parindent 0pt
\parskip 1ex plus .5ex minus .5ex

\def\small{\smallfont\textfont2=\smallsy\baselineskip=.8\baselineskip}

% newcolumn - force a new column.  Use sparingly, probably only for
% the first column of a page, which should have a title anyway.
\outer\def\newcolumn{\vfill\eject}

% title - page title.  Argument is title text.
\outer\def\title#1{{\titlefont\centerline{#1}}\vskip 1ex plus .5ex}

% section - new major section.  Argument is section name.
\outer\def\section#1{\par\filbreak
  \vskip 3ex plus 2ex minus 2ex {\headingfont #1}\mark{#1}%
  \vskip 2ex plus 1ex minus 1.5ex}

\newdimen\keyindent

% beginindentedkeys...endindentedkeys - key definitions will be
% indented, but running text, typically used as headings to group
% definitions, will not.
\def\beginindentedkeys{\keyindent=1em}
\def\endindentedkeys{\keyindent=0em}
\endindentedkeys

% paralign - begin paragraph containing an alignment.
% If an \halign is entered while in vertical mode, a parskip is never
% inserted.  Using \paralign instead of \halign solves this problem.
\def\paralign{\vskip\parskip\halign}

% \<...> - surrounds a variable name in a code example
\def\<#1>{{\it #1\/}}

% kbd - argument is characters typed literally.  Like the Texinfo command.
\def\kbd#1{{\tt#1}\null}        %\null so not an abbrev even if period follows

% beginexample...endexample - surrounds literal text, such a code example.
% typeset in a typewriter font with line breaks preserved
\def\beginexample{\par\leavevmode\begingroup
  \obeylines\obeyspaces\parskip0pt\tt}
{\obeyspaces\global\let =\ }
\def\endexample{\endgroup}

% key - definition of a key.
% \key{description of key}{key-name}
% prints the description left-justified, and the key-name in a \kbd
% form near the right margin.
\def\key#1#2{\leavevmode\hbox to \hsize{\vtop
  {\hsize=.75\hsize\rightskip=1em
  \hskip\keyindent\relax#1}\kbd{#2}\hfil}}

\newbox\metaxbox
\setbox\metaxbox\hbox{\kbd{M-x }}
\newdimen\metaxwidth
\metaxwidth=\wd\metaxbox

% metax - definition of a M-x command.
% \metax{description of command}{M-x command-name}
% Tries to justify the beginning of the command name at the same place
% as \key starts the key name.  (The "M-x " sticks out to the left.)
\def\metax#1#2{\leavevmode\hbox to \hsize{\hbox to .75\hsize
  {\hskip\keyindent\relax#1\hfil}%
  \hskip -\metaxwidth minus 1fil
  \kbd{#2}\hfil}}

% threecol - like "key" but with two key names.
% for example, one for doing the action backward, and one for forward.
\def\threecol#1#2#3{\hskip\keyindent\relax#1\hfil&\kbd{#2}\hfil\quad
  &\kbd{#3}\hfil\quad\cr}

%**end of header
\f

\title{GNU Emacs Reference Card}

\centerline{(for version \versionemacs)}

\section{Starting Emacs}

To enter GNU Emacs \versionemacs, just type its name: \kbd{emacs}

\section{Leaving Emacs}

\key{suspend Emacs (or iconify it under X)}{C-z}
\key{exit Emacs permanently}{C-x C-c}

\section{Files}

\key{{\bf read} a file into Emacs}{C-x C-f}
\key{{\bf save} a file back to disk}{C-x C-s}
\key{save {\bf all} files}{C-x s}
\key{{\bf insert} contents of another file into this buffer}{C-x i}
\key{replace this file with the file you really want}{C-x C-v}
\key{write buffer to a specified file}{C-x C-w}
\key{toggle read-only status of buffer}{C-x C-q}

\section{Getting Help}

The help system is simple.  Type \kbd{C-h} (or \kbd{F1}) and follow
the directions.  If you are a first-time user, type \kbd{C-h t} for a
{\bf tutorial}.

\key{remove help window}{C-x 1}
\key{scroll help window}{C-M-v}

\key{apropos: show commands matching a string}{C-h a}
\key{describe the function a key runs}{C-h k}
\key{describe a function}{C-h f}
\key{get mode-specific information}{C-h m}

\section{Error Recovery}

\key{{\bf abort} partially typed or executing command}{C-g}
\metax{{\bf recover} files lost by a system crash}{M-x recover-session}
\metax{{\bf undo} an unwanted change}{C-x u, C-_ {\rm or} C-/}
\metax{restore a buffer to its original contents}{M-x revert-buffer}
\key{redraw garbaged screen}{C-l}

\section{Incremental Search}

\key{search forward}{C-s}
\key{search backward}{C-r}
\key{regular expression search}{C-M-s}
\key{reverse regular expression search}{C-M-r}

\key{select previous search string}{M-p}
\key{select next later search string}{M-n}
\key{exit incremental search}{RET}
\key{undo effect of last character}{DEL}
\key{abort current search}{C-g}

Use \kbd{C-s} or \kbd{C-r} again to repeat the search in either direction.
If Emacs is still searching, \kbd{C-g} cancels only the part not matched.

\shortcopyrightnotice

\newcolumn
\section{Motion}

\paralign to \hsize{#\tabskip=10pt plus 1 fil&#\tabskip=0pt&#\cr
\threecol{{\bf entity to move over}}{{\bf backward}}{{\bf forward}}
\threecol{character}{C-b}{C-f}
\threecol{word}{M-b}{M-f}
\threecol{line}{C-p}{C-n}
\threecol{go to line beginning (or end)}{C-a}{C-e}
\threecol{sentence}{M-a}{M-e}
\threecol{paragraph}{M-\{}{M-\}}
\threecol{page}{C-x [}{C-x ]}
\threecol{sexp}{C-M-b}{C-M-f}
\threecol{function}{C-M-a}{C-M-e}
\threecol{go to buffer beginning (or end)}{M-<}{M->}
}

\key{scroll to next screen}{C-v}
\key{scroll to previous screen}{M-v}
\key{scroll left}{C-x <}
\key{scroll right}{C-x >}
\key{scroll current line to center, top, bottom}{C-l}

\key{goto line}{M-g g}
\key{goto char}{M-g c}
\key{back to indentation}{M-m}

\section{Killing and Deleting}

\paralign to \hsize{#\tabskip=10pt plus 1 fil&#\tabskip=0pt&#\cr
\threecol{{\bf entity to kill}}{{\bf backward}}{{\bf forward}}
\threecol{character (delete, not kill)}{DEL}{C-d}
\threecol{word}{M-DEL}{M-d}
\threecol{line (to end of)}{M-0 C-k}{C-k}
\threecol{sentence}{C-x DEL}{M-k}
\threecol{sexp}{M-- C-M-k}{C-M-k}
}

\key{kill {\bf region}}{C-w}
\key{copy region to kill ring}{M-w}
\key{kill through next occurrence of {\it char}}{M-z {\it char}}

\key{yank back last thing killed}{C-y}
\key{replace last yank with previous kill}{M-y}

\section{Marking}

\key{set mark here}{C-@ {\rm or} C-SPC}
\key{exchange point and mark}{C-x C-x}

\key{set mark {\it arg\/} {\bf words} away}{M-@}
\key{mark {\bf paragraph}}{M-h}
\key{mark {\bf page}}{C-x C-p}
\key{mark {\bf sexp}}{C-M-@}
\key{mark {\bf function}}{C-M-h}
\key{mark entire {\bf buffer}}{C-x h}

\section{Query Replace}

\key{interactively replace a text string}{M-\%}
% query-replace-regexp is bound to C-M-% but that can't be typed on
% consoles.
\metax{using regular expressions}{M-x query-replace-regexp}

Valid responses in query-replace mode are

\key{{\bf replace} this one, go on to next}{SPC {\rm or} y}
\key{replace this one, don't move}{,}
\key{{\bf skip} to next without replacing}{DEL {\rm or} n}
\key{replace all remaining matches}{!}
\key{{\bf back up} to the previous match}{^}
\key{{\bf exit} query-replace}{RET}
\key{enter recursive edit (\kbd{C-M-c} to exit)}{C-r}

\newcolumn
\section{Multiple Windows}

When two commands are shown, the second is a similar command for a
frame instead of a window.

{\setbox0=\hbox{\kbd{0}}\advance\hsize by 0\wd0
\paralign to \hsize{#\tabskip=10pt plus 1 fil&#\tabskip=0pt&#\cr
\threecol{delete all other windows}{C-x 1\ \ \ \ }{C-x 5 1}
\threecol{split window, above and below}{C-x 2\ \ \ \ }{C-x 5 2}
\threecol{delete this window}{C-x 0\ \ \ \ }{C-x 5 0}
}}
\key{split window, side by side}{C-x 3}

\key{scroll other window}{C-M-v}

{\setbox0=\hbox{\kbd{0}}\advance\hsize by 2\wd0
\paralign to \hsize{#\tabskip=10pt plus 1 fil&#\tabskip=0pt&#\cr
\threecol{switch cursor to another window}{C-x o}{C-x 5 o}

\threecol{select buffer in other window}{C-x 4 b}{C-x 5 b}
\threecol{display buffer in other window}{C-x 4 C-o}{C-x 5 C-o}
\threecol{find file in other window}{C-x 4 f}{C-x 5 f}
\threecol{find file read-only in other window}{C-x 4 r}{C-x 5 r}
\threecol{run Dired in other window}{C-x 4 d}{C-x 5 d}
\threecol{find tag in other window}{C-x 4 .}{C-x 5 .}
}}

\key{grow window taller}{C-x ^}
\key{shrink window narrower}{C-x \{}
\key{grow window wider}{C-x \}}

\section{Formatting}

\key{indent current {\bf line} (mode-dependent)}{TAB}
\key{indent {\bf region} (mode-dependent)}{C-M-\\}
\key{indent {\bf sexp} (mode-dependent)}{C-M-q}
\key{indent region rigidly {\it arg\/} columns}{C-x TAB}
\key{indent for comment}{M-;}

\key{insert newline after point}{C-o}
\key{move rest of line vertically down}{C-M-o}
\key{delete blank lines around point}{C-x C-o}
\key{join line with previous (with arg, next)}{M-^}
\key{delete all white space around point}{M-\\}
\key{put exactly one space at point}{M-SPC}

\key{fill paragraph}{M-q}
\key{set fill column to {\it arg}}{C-x f}
\key{set prefix each line starts with}{C-x .}

\key{set face}{M-o}

\section{Case Change}

\key{uppercase word}{M-u}
\key{lowercase word}{M-l}
\key{capitalize word}{M-c}

\key{uppercase region}{C-x C-u}
\key{lowercase region}{C-x C-l}

\section{The Minibuffer}

The following keys are defined in the minibuffer.

\key{complete as much as possible}{TAB}
\key{complete up to one word}{SPC}
\key{complete and execute}{RET}
\key{show possible completions}{?}
\key{fetch previous minibuffer input}{M-p}
\key{fetch later minibuffer input or default}{M-n}
\key{regexp search backward through history}{M-r}
\key{regexp search forward through history}{M-s}
\key{abort command}{C-g}

Type \kbd{C-x ESC ESC} to edit and repeat the last command that used the
minibuffer.  Type \kbd{F10} to activate menu bar items on text terminals.

\newcolumn
\title{GNU Emacs Reference Card}

\section{Buffers}

\key{select another buffer}{C-x b}
\key{list all buffers}{C-x C-b}
\key{kill a buffer}{C-x k}

\section{Transposing}

\key{transpose {\bf characters}}{C-t}
\key{transpose {\bf words}}{M-t}
\key{transpose {\bf lines}}{C-x C-t}
\key{transpose {\bf sexps}}{C-M-t}

\section{Spelling Check}

\key{check spelling of current word}{M-\$}
\metax{check spelling of all words in region}{M-x ispell-region}
\metax{check spelling of entire buffer}{M-x ispell-buffer}
\metax{toggle on-the-fly spell checking}{M-x flyspell-mode}

\section{Tags}

\key{find a tag (a definition)}{M-.}
\key{find next occurrence of tag}{C-u M-.}
\metax{specify a new tags file}{M-x visit-tags-table}

\metax{regexp search on all files in tags table}{M-x tags-search}
\metax{run query-replace on all the files}{M-x tags-query-replace}
\key{continue last tags search or query-replace}{M-,}

\section{Shells}

\key{execute a shell command}{M-!}
\key{execute a shell command asynchronously}{M-\&}
\key{run a shell command on the region}{M-|}
\key{filter region through a shell command}{C-u M-|}
\key{start a shell in window \kbd{*shell*}}{M-x shell}

\section{Rectangles}

\key{copy rectangle to register}{C-x r r}
\key{kill rectangle}{C-x r k}
\key{yank rectangle}{C-x r y}
\key{open rectangle, shifting text right}{C-x r o}
\key{blank out rectangle}{C-x r c}
\key{prefix each line with a string}{C-x r t}

\section{Abbrevs}

\key{add global abbrev}{C-x a g}
\key{add mode-local abbrev}{C-x a l}
\key{add global expansion for this abbrev}{C-x a i g}
\key{add mode-local expansion for this abbrev}{C-x a i l}
\key{explicitly expand abbrev}{C-x a e}

\key{expand previous word dynamically}{M-/}

\section{Miscellaneous}

\key{numeric argument}{C-u {\it num}}
\key{negative argument}{M--}
\key{quoted insert}{C-q {\it char}}

\newcolumn
\section{Regular Expressions}

\key{any single character except a newline}{. {\rm(dot)}}
\key{zero or more repeats}{*}
\key{one or more repeats}{+}
\key{zero or one repeat}{?}
\key{quote special characters}{\\}
\key{quote regular expression special character {\it c\/}}{\\{\it c}}
\key{alternative (``or'')}{\\|}
\key{grouping}{\\( {\rm$\ldots$} \\)}
\key{shy grouping}{\\(:? {\rm$\ldots$} \\)}
\key{explicit numbered grouping}{\\(:NUM {\rm$\ldots$} \\)}
\key{same text as {\it n\/}th group}{\\{\it n}}
\key{at word break}{\\b}
\key{not at word break}{\\B}

\paralign to \hsize{#\tabskip=10pt plus 1 fil&#\tabskip=0pt&#\cr
\threecol{{\bf entity}}{{\bf match start}}{{\bf match end}}
\threecol{line}{^}{\$}
\threecol{word}{\\<}{\\>}
\threecol{symbol}{\\_<}{\\_>}
\threecol{buffer}{\\`}{\\'}
%% FIXME: "`" and "'" isn't displayed correctly in the output PDF file

\threecol{{\bf class of characters}}{{\bf match these}}{{\bf match others}}
\threecol{explicit set}{[ {\rm$\ldots$} ]}{[^ {\rm$\ldots$} ]}
\threecol{word-syntax character}{\\w}{\\W}
\threecol{character with syntax {\it c}}{\\s{\it c}}{\\S{\it c}}
\threecol{character with category {\it c}}{\\c{\it c}}{\\C{\it c}}
}

\section{International Character Sets}

\key{specify principal language}{C-x RET l}
\metax{show all input methods}{M-x list-input-methods}
\key{enable or disable input method}{C-\\}
\key{set coding system for next command}{C-x RET c}
\metax{show all coding systems}{M-x list-coding-systems}
\metax{choose preferred coding system}{M-x prefer-coding-system}

\section{Info}

\key{enter the Info documentation reader}{C-h i}
\key{find specified function or variable in Info}{C-h S}
\beginindentedkeys

Moving within a node:

\key{scroll forward}{SPC}
\key{scroll reverse}{DEL}
\key{beginning of node}{b}

Moving between nodes:

\key{{\bf next} node}{n}
\key{{\bf previous} node}{p}
\key{move {\bf up}}{u}
\key{select menu item by name}{m}
\key{select {\it n\/}th menu item by number (1--9)}{{\it n}}
\key{follow cross reference  (return with \kbd{l})}{f}
\key{return to last node you saw}{l}
\key{return to directory node}{d}
\key{go to top node of Info file}{t}
\key{go to any node by name}{g}

Other:

\key{run Info {\bf tutorial}}{h}
\key{look up a subject in the indices}{i}
\key{search nodes for regexp}{s}
\key{{\bf quit} Info}{q}

\endindentedkeys

\newcolumn
\section{Registers}

\key{save region in register}{C-x r s}
\key{insert register contents into buffer}{C-x r i}

\key{save value of point in register}{C-x r SPC}
\key{jump to point saved in register}{C-x r j}

\section{Keyboard Macros}

\key{{\bf start} defining a keyboard macro}{C-x (}
\key{{\bf end} keyboard macro definition}{C-x )}
\key{{\bf execute} last-defined keyboard macro}{C-x e}
\key{append to last keyboard macro}{C-u C-x (}
\metax{name last keyboard macro}{M-x name-last-kbd-macro}
\metax{insert Lisp definition in buffer}{M-x insert-kbd-macro}

\section{Commands Dealing with Emacs Lisp}

\key{eval {\bf sexp} before point}{C-x C-e}
\key{eval current {\bf defun}}{C-M-x}
\metax{eval {\bf region}}{M-x eval-region}
\key{read and eval minibuffer}{M-:}
\metax{load a Lisp library from {\bf load-path}}{M-x load-library}

\section{Simple Customization}

\metax{customize variables and faces}{M-x customize}

% The intended audience here is the person who wants to make simple
% customizations and knows Lisp syntax.

Making global key bindings in Emacs Lisp (example):

\beginexample%
(global-set-key (kbd "C-c g") 'search-forward)
(global-set-key (kbd "M-\#") 'query-replace-regexp)
\endexample

\section{Writing Commands}

\beginexample%
(defun \<command-name> (\<args>)
  "\<documentation>" (interactive "\<template>")
  \<body>)
\endexample

An example:

\beginexample%
(defun this-line-to-top-of-window (line)
  "Reposition current line to top of window.
With prefix argument LINE, put point on LINE."
  (interactive "P")
  (recenter (if (null line)
                0
              (prefix-numeric-value line))))
\endexample

The \kbd{interactive} spec says how to read arguments interactively.
Type \kbd{C-h f interactive RET} for more details.

\copyrightnotice

\bye
\f
% Local variables:
% compile-command: "pdftex refcard"
% End: