@Section
   @Title { Getting started }
   @Tag { start }
@Begin
@PP
Suppose you want to produce the following little document:
@CD @Box margin { 1.3c } 7.0c @Wide 9c @High {
@Display @Heading { Introduction by W. J. Harvey }
harvey.w.j @Index { Harvey, W. J. }
For Virginia Woolf, @I Middlemarch was `the magnificent book
which for all its imperfections is one of the few English novels
written for grown-up people.'
@PP
She was, no doubt, thinking of George Eliot's unblinking but
eliot.g @Index { Eliot, George }
compassionate delineation of her characters, of the subtlety of
psychological analysis and the maturity of moral comment which
underlie this complex and varied novel of English provincial
life in the early nineteenth century.
}
Unlike word processing and desktop publishing systems, with Lout you
cannot see and edit your document on the screen in this finished
form.  Instead, you edit an ordinary text file, in which your text is
augmented with symbols that mark out the headings, paragraphs, and so
on.  Although it would be nice to be able to see and edit the finished
form, working with a text file and symbols does have some compensating
advantages.
@PP
The first step in producing your introduction to @I Middlemarch is to
use the text editor of your choice to construct this text file:
@ID @OneRow @Code {
"@SysInclude { doc }"
"@Doc @Text @Begin"
"@Display @Heading { Introduction by W. J. Harvey }"
"For Virginia Woolf, @I Middlemarch was `the magnificent book which for all its"
"imperfections is one of the few English novels written for grown-up people.'"
"@PP"
"She was, no doubt, thinking of George Eliot's unblinking but compassionate"
"delineation of her characters, of the subtlety of psychological analysis and"
"the maturity of moral comment which underlie this complex and varied novel"
"of English provincial life in the early nineteenth century."
"@End @Text"
}
Comparing this with the finished form, it's easy to guess that
@Code "@I" is a symbol that causes the following thing to be printed
in italics, and that @Code "@PP" starts a new paragraph.  The other
symbols are not much harder.
@PP
@Code "@SysInclude { doc }" instructs Lout to read a @I { setup file }
called {@Code "doc"}, in which the symbols are defined.  Setup files
are the subject of Chapter {@NumberOf changes}, but you can go a long
way without worrying about them.  @Code "@Doc @Text @Begin" and
@Code "@End @Text" have no visible effect, but they must bracket the
document as a whole.  Again, you don't have to know what they are for.
@PP
That explains everything except the part that produces the heading.  It's
an interesting glimpse of the way that Lout's symbols cooperate with
each other:
@ID @Code "@Display @Heading { Introduction by W. J. Harvey }"
The @Code "@Display" symbol does the centring and leaves space above
and below, while @Code "@Heading" switches to a bold font.  The braces
group the words of the heading together so that these symbols apply to
all of it; without them they would apply to just the first word.  All
this is explained in detail in Sections {@NumberOf objects}
and {@NumberOf spaces}.
@PP
Once the file is ready, the next step is to get it processed by the
Basser Lout interpreter.  If the file's name is {@Code "intro"},
the command for this on the Unix
@FootNote { Unix is a trademark. }
operating system is
@ID @Code "lout intro > intro.ps"
The output is the PostScript
@FootNote { PostScript is a trademark of Adobe Systems, Inc. }
file {@Code "intro.ps"}, which is suitable for printing on many laser
printers and other devices.  There are programs that show you the
result on your screen as well, although you won't be able to edit it
there.  You can also get plain text output (Section {@NumberOf plain})
and PDF output.
@PP
There are a few points that often confuse people as they begin, so we'll
treat them briefly now with pointers to later sections where they are
done properly.
@PP
Some characters are symbols that produce special effects -- for
example, @Code "{" and @Code "}" produce grouping -- and to turn off
these effects the characters must be enclosed in double quotes:  @Code
"\"{\"" produces "{".  The complete set of these special characters is
@ID @Code "/    |    &    {    }    #    @    ^   ~   \\   \""
Section {@NumberOf characters} treats unusual characters in full detail.
@PP
Symbols like @Code "@Doc" and @Code "@Text" must be separated from
each other by one or more spaces, otherwise Lout will think they are part
of one symbol.  See Section {@NumberOf spaces} for the details.
@PP
People familiar with other systems might expect that leaving a blank line would
cause Lout to start a new paragraph; but this is not so, you must use a
paragraph symbol.  Lout will ordinarily take notice of how many spaces you type
between words (Section {@NumberOf spaces}), but it will mimic the spacing rules
of two other systems, troff and @TeX, if you prefer (Section {@NumberOf white}).
@PP
When Lout runs, you might see some error messages containing the words
errors. @Index { errors }
`unresolved cross reference' and `no destination point' -- not on file
@Code "intro" above, but on more complicated ones (anything with a footnote,
for example).  These just mean that you have to run the @Code "lout" command
again to finish off the complicated things (Section {@NumberOf cross}), and
they will gradually go away.  Of course, if you see error messages about
missing braces, unknown symbols, and so on, you need to revise your file.  Lout
will tell you the line number of the problem, and how far along the line it is.
@PP
@BI { WARNING: }  Lout allows documents to cause arbitrary system commands
to be executed.  These typically do useful things such as format computer
programs and uncompress graphics files, but it is possible for a
malicious person to send you a document which includes a command to delete
all your files, send abusive mail to the President of the United States in
your name, etc.  You can protect yourself against this possibility by using
the `safe execution' flag:
@ID @Code "lout -S suspect.document > out.ps"
Then no system commands will be executed; instead, Lout will print them so
that you can confirm for yourself that they are safe before running again
without the flag.  These system commands are Lout's only potentially unsafe
features, but you also need to worry about whether the resulting PostScript
file contains malicious code, since the document may direct Lout to include
arbitrary PostScript code in the output.  The safe execution of PostScript
programs is a matter for PostScript interpreters, not for Lout.  For example,
the popular Ghostview program has a @Code "-safer" command line option,
which is rumoured to disable unsafe PostScript features.
@End @Section
