% PROGRAMMER'S MANUAL in Plain TeX

\input formlett.sty

% FONTS
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\def\makefootline{\baselineskip=24pt \line{\the\footline}}
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\hbox to \hsize
 {{\tenrm Jiang Z ~~~{\tensl Formlett: ~for letters to multiple receivers}
\hss \folio}}}

\leftline{\hbold FORMLETT: ~~~for Letters to Multiple Receivers}
\bigskip


{\advance\leftskip by13mm \overfullrule=0pt
\advance\rightskip by 20mm %28mm
\sl
\noindent Zhuhan JIANG\par
\noindent School of Computing and Information Technology,
 University of Western Sydney, Victoria Road, Parramatta NSW 2150, Australia.
{\sl ~~Email}:~z.jiang@uws.edu.au\par
\medskip
\rm\smooth
\noindent (Last updated on 26 May 2003)\par
\medskip

\noindent
In this article, the author explains how to use a form-letter
style {\tt formlett.sty}, designed for plain \TeX\ and \LaTeX
\ or \LaTeX2e. {\tt formlett.sty} supports different parameter input
methods, parameter naming and defaulting mechanism, as well as
facilities for previewing parameter positions and printing
labels. It is written for the purpose of being powerful, robust
and above all easy to use.\par }


\begincolumns

{\lbold Introduction}

\smallskip

In this modern world of ours, we often need to send a set of form
letters, personalised or non-personalised, to many receivers at
the same time. Or perhaps we would like to have a collection of
business letters or information brochures which we would like to
call upon {\sl instantly} whenever we need them.

\medskip

Our purpose here is therefore to describe a comprehensive
implementation of such a macro system, handling form letters
under \TeX\ or \LaTeX. The main objective is to provide an easy
way to output many form letters with  their own parameters, with
or without the use of multiple files. There will be a coherent
and simple format for putting parameters inside a form letter,
with a number of helping facilities for such as naming parameters
and previewing their positions. A minimum support for printing
mailing labels is also provided.


\medskip

The concept of macros [1] for form letters is not new: there
already exist macros in this connection such as {\tt merge}, {\tt
textmerg} and {\tt address} to name a few, see [2,3] for further
details. Our stress here is therefore laid on the ease to use,
along with the power and the robustness of the macros.

\bigskip
{\lbold Format}

\smallskip

In this section, we always assume that the file {\tt formlett.sty}
or {\tt formlett.tex} of version {\tt 2.3} has
already been input. Certain version of {\tt formlett.sty} can be
obtained via anonymous ftp from CTAN sites at
{\tt macros /generic}.

\medskip

Essentially, each form letter, or letter format or letter
template, will be included between {\tt \string\beginletter} and
{\tt \string\endletter}. Letter parameters that will be specified
later on for each particular letter can be given by {\tt
\string\paras[<m>][<n>]}, representing the {\tt <m>}-th parameter
of the {\tt<n>}-the parameter group, at the positions you want
them to be. Let a cluster denote a complete collection of
parameters that may be specified for a form letter. Then we can
specify letter parameters group by group for a cluster such that
inside each group the parameters are given {\sl sequentially} and
a termination of one group should not affect the
resynchronisation for the next group. For instance we can keep
the address of a receiver as a single group, as it often contains
different number of (parameter) lines.


\medskip
We often want to treat a particular group of letter
parameters somewhat uniformly. This can be achieved by one of the
following commands

\setraw
  \blockparas[<m>][<n>][<pre>][<post>]
  \addressparas[<m>][<n>][<width>][<indent>]
\unsetraw

They represent parameters in the {\tt<n>}-th group, from the {\tt
<m>}-th to the last parameter of that group. For {\tt
\string\blockparas}, tokens {\tt <pre>} and {\tt <post>} are
those to be added in front and behind respectively each of the
legitimate parameters mentioned above. If {\tt <post>} is
{\tt\string\relax}, it will then not be appended at the end.
Instead, each chosen parameter will be put into a {\tt $\{\}$}-
pair before preceded by the token {\tt <pre>}. The reason for
this exception is that while {\tt <pre> and <post>} are meant to
be the front and end macros for each selected parameter, in the
case of {\tt <post>} being {\tt \string\relax}, we may regard
{\tt<pre>} as {\sl acting upon} each chosen parameter.


\medskip
The command {\tt \string\addressparas}, however, uses
{\tt \string\blockparas} indirectly and will put the chosen
parameters into a box of width {\tt<width>}. If any selected
parameter is longer than {\tt<width>}, then the line will be
wrapped around, with all wrapped potions being indented by an
{\tt<indent>}. This may be used to deal with very long address
lines. Incidentally, we may use {\tt \string\textbox} or {\tt
\string\addressbox} or {\tt \string\ADDRESSBOX} to control the
width of a single parameter. The general format reads


\setraw
  \textbox[<width]{<materials>}
  \addressbox[<width>][<indent>]{<materials>}
  \ADDRESSBOX{<width>}{<indent>}{<materials>}
\unsetraw

where the meaning of the macro parameters are self-explanatory.


\medskip

For the macro parameters, we have for convenience provided the
following defaults for those in the squared brackets

\setraw
  <m>=1
  <n>=1
  <pre>=\noindent
  <post>=\par
  <width>= 8truecm
  <indent>= 1.5em
\unsetraw

This way, for instance, {\tt\string\paras[1][1]} is equivalent
to any of the following commands

\setraw
  \paras, \paras[1], \paras[][1],
  \paras[1][], \paras[][]
\unsetraw

and the following three commands are also the same

\setraw
  \addressbox{one address line}
  \addressbox[8truecm]{one address line}
  \addressbox[][1.5em]{one address line}
\unsetraw


\medskip

Incidentally this is the reason why we used the second parameter
{\tt<n>} to represent the group number: the defaults can often be
dropped off more frequently. By default, all letter parameters
specified will be put into a group environment before putting
them into the form letter, unless {\tt \string\localparasfalse}
is issued beforehand.

\medskip
To output a new letter entity, i.e a complete letter,
we may use


\setraw
  \moreletter
    para-1-1;para-1-2;para-1-3; ...
   +para-2-1;para-2-2;...
   +   ...
   +para-n-1;para-n-2; ... ;para-n-m !
\unsetraw


where \lq{\tt ;}\rqs separate parameters inside a same group,
\lq{\tt +}\rqs separates groups, \lq{\tt !}\rqs ends a cluster of
parameters, and \lq{\tt ...}\rqs represent further letter
parameters. These three tokens are nothing special: we may change
them  to for instance \lq{\tt ....}\rq, \lq{\tt ----}\rqs and
\lq{\tt ====}\rqs respectively by {\tt \string\blockmarks}, and
change them back to \lq{\tt ; + !}\rqs by {\tt
\string\defaultmarks}.  For more general case, use

\setraw
  \delimiters{<A>}{<B>}{<C>}
\unsetraw

where {\tt <A>}, {\tt <B>} and {\tt <C>} are the new toks
replacing \lq{\tt ; + !}\rqs respectively. If we have to use
these three special characters or tokens inside our {\sl letter
parameters}, then use {\tt \string\pstr}, {\tt\string\gstr} and
{\tt\string\cstr} respectively instead.

\medskip

For the case of many clusters, we may enclose them, separated by
any white spaces or empty lines, between {\tt
\string\beginpilemode} and {\tt \string\endpilemode} so that we
don't have to put {\tt \string\moreletter} in front of each
cluster of parameters.


\medskip
We may also enter letter parameters line by line. In other words,
we may essentially replace \lq{\tt;}\rqs in the {\tt
\string\moreletter} format by a normal line break. In this case,
we shall put  clusters of parameters between {\tt
\string\beginblockmode} and {\tt \string\endblockmode}.  Thus the
following commands


\setraw
  \beginblockmode
     <para-1-1>
     <para-1-2>
       +       letter one

     <para-2-2>
       !

     <addr-1-1>
     <addr-1-2>
       !       letter two
  \endblockmode
\unsetraw


will produce the required form letter for each cluster of
parameters. The general rules are as follows:

{\parindent=1.5em
\item{$\bullet$} If a line contains {\tt \string\endblockmode} or {\tt !}
or {\tt +}, then everything else on that line is ignored and that
line serves as an end/cluster/group marking line in the given
priority order.

\item{$\bullet$} Leading and trailing empty lines before or after
a complete cluster will be ignored, unless \lq{\tt ;}\rqs is
there to force the next (empty) line as a starting parameter.
\par }

Obviously {\tt \string\blockmarks} provides a more sensible
delimiters for the {\tt blockmode}, under which we could have

\setraw
  \blockmarks\beginblockmode
    .......    force next empty line active

   <para-1-2>
   ------- -  mark end of 1st group

   <para-2-2>
   <para-2-3>
   ========   end of cluster

   <other clusters>
  \endblockmode
\unsetraw

\medskip
A simpler and perhaps more often encountered scenario is
to use names and addresses only. In this case, there will be
essentially only {\sl one} group of parameters for each cluster.
Thus we may use empty lines to delimit the clusters, and use line
by line mode for the individual parameters. This way, each
block of consecutive nonempty lines in

\setraw
  \beginlinemode
    <name-1>
    <address-1-1>
    <address-1-2>

    <name-2>
    <1st part of addr-2-1>  %
    <continued part of line addr-2-1>

    <name-3>      % letter three
  \endlinemode
\unsetraw


will output a new complete letter, corresponding to the specified
letter parameters.


\medskip
{\smooth
Ideally, the name--address entries will be produced by a database
utility. Since they often contain special characters such as \lq
{\tt \#}\rqs and \lq{\tt \$}\rqs explicitly, we may wish to
change such characters in the parameters to the normal printable
ones. For this purpose, we could use correspondingly the pair
{\tt \string\beginrawblockmode$\{$<token>$\}$} with {\tt
\string\endrawblockmode} or the pair {\tt
\string\beginrawlinemode$\{$<token>$\}$} with {\tt
\string\endrawlinemode}. If {\tt <token>} is not empty, then we
use {\tt <token>} in place of {\tt \string\endrawblockmode} or
{\tt \string\endrawlinemode}. In other words, {\tt <token>} is
the password to leave the raw text mode.  Since database utility
will in general produce a {\sl fixed} number of {\tt <m>} lines
for each cluster of parameters, we may use {\tt
\string\begindatamode[<token>]$\{$<m>$\}$} and {\tt
\string\enddatamode} (or {\tt<token>}) in place of {\tt
\string\beginrawlinemode} and {\tt\string\endrawlinemode} so that
each {\tt<m>} raw text lines, including the empty ones, will eject
a form letter.
}


\medskip

It is often desirable that a letter form or format and the actual
parameters be kept in different files: it will help in archiving
and retrieving form letters. Furthermore, if a letter is quite
long such that the \TeX\ can't hold it in the memory, then we
{\sl have to} keep the letter content in a separate file.
Essentially we need to save everything between
{\tt\string\beginletter} and {\tt \string\endletter} into a
separate file, say, {\tt letter.let}, then later on use
{\tt\string\inputletter$\{$letter.let$\}$} to load in the letter
format. Should one prefer to keep everything inside a {\sl single}
file, however, he may use {\tt\string\beginfile [{\it
password}]$\{${\it file.ext}$\}$} and {\tt\string\endfile} (or
{\it password}) to create files such as {\tt letter.let}
mentioned above as a temporary scratch file. We note that {\tt
letter.let} will not contain {\tt\string\beginletter} and
{\tt\string\endletter} as {\tt \string\inputletter} will add them
properly for us. Also the extension {\tt .let} is preferred in
this connection as it can indicate that this type of format file
should not quite be regarded as the normal \TeX\ files.

\medskip

Likewise, it is also desirable to have a separate address or
general letter parameter file. For the address file, we remark
that we have to keep the pairing {\tt \string\beginlinemode} with
{\tt \string\endlinemode} or {\tt\string\beginblockmode} with
{\tt \string\endblockmode} inside the address file, if we are to
use any of them for some content of that file. Moreover, an
extension {\tt .adr} is recommended for such files. Thus for a
letter format or template saved in {\tt letter.let}, we may
choose {\tt letter.adr} as the name for the related address file.

\medskip
After a letter format is completed for sometime, one may have
difficulty in recalling what those parameters should refer to
when using the form letter again. For this purpose, we provide
a simple mechanism with {\tt\string\paranames} and {\tt
\string\showparas}. To be more precise, if one puts {\tt
\string\paranames\ name-1-1; ...; <etc>!} at the very beginning of
the letter format, then one can use {\tt\string\showparas}
outside to output a letter with its parameters replaced by their
names.

\medskip

An alternative way, or rather a way of highlighting the positions
of the letter parameters is to use {\tt\string\preview}. Under
{\tt\string\preview}, or {\tt \string\previewtrue}, all
parameters given by {\tt\string\paras[<m>][<n>]} will be boxed
with double borderlines, similar to {\tt \previewtrue
\paras[3][2]}, the number {\tt<n>-<m>} inside (corresponding to
{\tt 2-3} in the shown box) denotes the {\tt<m>}-th parameter of
the {\tt <n>}-th group. However, the parameters given by
{\tt\string\blockparas} or {\tt\string\addressparas} will be
boxed with triple borderlines. Moreover, the macro parameters
{\tt<pre>} and {\tt <post>} will also be displayed explicitly.
Since {\tt\string\addressparas} is essentially a special way of
using {\tt\string\blockparas}, it is highlighted via that for the
{\tt\string\blockparas}. In particular,
{\tt\string\blockparas[3][6][\string\x][\string\y]} for instance
will display under {\tt \string\preview} the following box

\smallskip
{\previewtrue  \blockparas[3][6][\x][\y]}


\medskip

Sometimes we may want to have each given {\sl empty} letter
parameter automatically replaced by a particular {\sl default}
parameter. This can be easily done by using {\tt
\string\loaddefaultparas} inside your letter format, i.e.
essentially between {\tt \string\beginletter} and {\tt
\string\endletter}, before any calling of the letter parameters
via {\tt \string\paras} etc.  Of course, the effect of {\tt
\string\loaddefaultparas} is nil unless a command {\tt
\string\paradefaults} is issued inside or (better still) outside
the letter format. We note that {\tt \string\paradefaults} takes
the macro parameters in the exact way as {\tt \string\paranames}
does. One note of caution: {\tt \string\paradefaults} and {\tt
\string\paranames} always use the default delimiters \lq{\tt ; +
!}\rqs no matter how you changed them via {\tt
\string\delimiters}. This is to avoid unnecessary complications.

\medskip

We note that printing labels is no more than designing a special
letter template. The mechanism provided in {\tt formlett} however
is to pick a subblock of parameters as the address. Basically all
the form letter output inside {\tt\string\beginlabels} and
{\tt\string\endlabels} will produce labels instead, taking the
first parameter group as the address by default (see Appendix for
more details). Incidentally, labels can be printed in single or
double columns depending upon the choice of label width.

\medskip

To conclude this section, we remark that if you want to put {\tt
\string\input\ {\sl filename} } into a letter parameter, make
sure that there is a {\sl nontrivial} space following the {\sl
filename}. To be on the safe side, always use {\tt
\string\inputfile $\{$\sl filename.ext$\}$} instead. Also {\tt
<!>}, when output to screen, is an invitation to read the log
file for a warning message.

\bigskip
{\lbold Example}


\smallskip

The following is an example. If you are running plain \TeX, add
{\tt\string\input\ formlett} at the top. But if you are running
\LaTeX, then just add at the top the line

\linecount=1\relax
\stt\beginrawlist[][][4][][][3.3in]{}
  \documentstyle[formlett]{article}
  \begin{document}
\endrawlist
\rm



The line numbering on the right hand side is for reference only,
as in the other occurrences later on. The example reads as
follows.

\medskip

\stt\beginrawlist[][][4][][][3.3in]{}
  \beginletter
  \paranames             % optional
    \tt<<FULL NAME>>;%
    \tt<<ADDRESS-etc>>;%
   +\tt<<GIVEN NAME>>;%
    \tt<<MISSING ITEM>>;%
    \tt<<PHONE NUMBER>>!
  \loaddefaultparas      % optional

  \NOPAGENUMBERS\parindent=0pt
  \noindent{\it\paras[1]}\par
  \blockparas[2]\par\bigskip

  Dear \paras[1][2],\par\medskip
  We have been looking for
  \paras[2][2] for quite a while
  without any luck, could you help
  us out? If so, please ring
  \paras[3][2]. \par\medskip
  Cheers!\hfill Michael\vfill\eject
  \endletter
  \preview \showparas
\endrawlist
\rm


\medskip

%%%%%%%%%%%%
% letter top
%%%%%%%%%%%%

  \beginletter
\sl
\hsize=3.1in\relax
\medskip
  \paranames             % optional
    \tt<<FULL NAME>>;%
    \tt<<ADDRESS-etc>>;%
   +\tt<<GIVEN NAME>>;%
    \tt<<MISSING ITEM>>;%
    \tt<<PHONE NUMBER>>!
  \loaddefaultparas      % optional

  \NOPAGENUMBERS\parindent=0pt\overfullrule=0pt
  \noindent{\it\paras[1]}\par
  \blockparas[2]\par\medskip

  Dear \paras[1][2],

  \smallskip
  We have been looking for
  \paras[2][2] for quite a while
  without any luck, could you help
  us out? If so, please ring
  \paras[3][2]. \par\medskip
  Cheers!\hfill Michael\par %\vfill\eject
\medskip
  \endletter

%%%%%%%%%%%%
% letter end
%%%%%%%%%%%%


The above is a typical letter format or form letter. Command
{\tt\string\preview} in the last line gives

{\preview}

and, the name of the parameters are displayed via
{\tt\string\showparas} as follows

\showparas


\medskip

In other words, we can have a good understanding about what a
letter format does {\sl without} reading its source code, which
will be very handy for archiving and retrieving letter templates.
To provide defaults for letter parameters and output new letters
via {\tt blockmode}, we may add \par

\medskip
\stt\beginrawlist[][][4][][][3.3in]{}
  \paradefaults       % optional
    To whom this may concern
   +Sir or Madam;something;%
    061-225-9905!

  \blockmarks
  \beginrawblockmode{}

  Mrs L Stenson
  #1-20 Sunset Street
  Hillside, Norway
  ------
  Louise
  a Bible
  220-8888
  =========

  ......

  Above empty line active

  \endrawblockmode
\endrawlist
\rm

%%%%%%%%%%%%
% 1st letter top
%%%%%%%%%%%%
\paradefaults       % optional
 To whom this may concern
+Sir or Madam;something;%
 061-225-9905!

%%%%%%%%%%%%
% 1st letter end
%%%%%%%%%%%%

\medskip
We note the parameters contain special characters \#.  That is
the reason why we used {\tt\string\beginrawblockmode}. Now
suppose we have to wrap a very long address line, we could use
{\tt \string\addressbox} to control an {\sl individual}
parameter. The following is a typical case

\medskip
\stt\beginrawlist[][][4][][][3.3in]{}
  \defaultmarks
  \moreletter
     S Wales,;%
     \addressbox[2in][1em]{%
     University of Manchester Institute
     of Science and Technology, This is
     a long address line: it will be
     wrapped up automatically.}%
   +;a \TeX\ package \gstr\ manual and
     many more (\cstr)!
\endrawlist
\rm

\medskip
which is manifested in the following output

%%%%%%%%%%%%
% 2nd letter top
%%%%%%%%%%%%
\defaultmarks
\moreletter
 S Wales,;%
 \addressbox[2in][1em]{%
 University of Manchester Institute
 of Science and Technology, This is
 a long address line: it will be
 wrapped up automatically.}%
+;a \TeX\ package \gstr\ manual and
 many more (\cstr)!
%%%%%%%%%%%%
% 2nd letter end
%%%%%%%%%%%%


\medskip

Please note that the default parameters have been used there. In
the case of putting {\sl only} name and address into a form
letter, we may typically use {\tt linemode} via e.g.

\medskip
\stt\beginrawlist[][][4][][][3.3in]{}
  \beginlinemode
    Z Jiang
    UNE, Arimdale

    T Ribbons
    UMIST, Manchester
  \endlinemode
  \end{document}
\endrawlist
\rm

\medskip

If one saves lines 4-22 to file {\tt myletter.let}, lines 25-63
or simply lines 57-63 to file {\tt myletter.adr}, then we can for
instance produce via \LaTeX\ the form letter for multiple
receivers by

\setraw
  \documentstyle[formlett]{article}
  \begin{document}
  \inputletter{myletter.let}
  \showparas \preview
  \paradefaults To whom it may concern!
  \inputfile{myletter.adr}
  \beginlabels % 1st parameter group as address
  \inputfile{myletter.adr} % for labels
  \endlabels
  \end{document}
\unsetraw

{\smooth

If one puts commands {\tt\string\beginlables} and
{\tt\string\endlabels} at e.g. immediately after line 2 and 63
respectively, then one gets all the posting labels instead. If
one puts commands {\tt\string\beginfile$\{$scratch.adr$\}$} and
{\tt\string\endfile} there respectively, then by adding after
{\tt\string\endfile} the commands

\setraw
  \inputfile{scratch.adr}
  \beginlabels \inputfile{scratch.adr} \endlabels
\unsetraw

one gets both form letters and the labels. If one insists on not
writing out auxiliary scratch files, then use {\tt \string\input
\ formlett.sty \string\initstyle\ [{\it styles}]$\{${\tt
article}$\}\{${\it preamble}$\}$} to replace {\tt
\string\documentstyle\ [formlett, {\it styles}]$\{$article$\}$
{\it preamble} \string\begin$\{$document$\}$}, which will be
valid for \LaTeX\  but ignored for \TeX\ , and will enable one to
use {\tt \string\labelsquit} at the end to read in the current
document again with all the letters there converted into the
corresponding labels. If you only want to execute certain
commands the first time round (i.e. before {\tt
\string\labelsquit} re-reads the file again), use {\tt
\string\firstread$\{${\it commands}$\}$} for this purpose.

}


\bigskip
{\lbold Macros}


\smallskip

One of the main technical features of this set of macros is the
extensive use of arrays, both one dimensional and two
dimensional. The one dimensional array {\tt STK} that we use is
essentially an user-defined stack, while the two dimensional
arrays {\tt LET} and {\tt DEF} are more like structure or record
in other programming languages. First let us make clear that an
array (or stack) of name, say {\tt ABC}, will contain elements
{\tt \string\ABC\it m\tt\t} for one dimensional and {\tt
\string\ABC\it m\tt*\it n\tt\t} for two dimensional case, where
$m$ and $n$ are some non-negative integers representing row and
column numbers respectively. The first element, if necessary,
will be used to denote the length of that raw. Thus, {\tt
\string\ABC1*0\t} for instance will denote the number of elements
in the first raw of a two dimensional array {\tt ABC}.


\medskip

Let us now look at how a mechanism of defaulting {\sl macro}
parameters is formulated. For this purpose, we first define a
stack {\tt STK} and its stack pointer {\tt \string\STKcount} by

\setraw
  \def\make@STKcount{\csname newcount\endcsname
    \STKcount\global\STKcount=0\relax}
  \ifx\STKcount\undefined@\def\next{%
    \make@STKcount}\else\def\next{}\fi\next
  \long\def\push#1{\global
    \advance\STKcount1\relax
    \expandafter\gdef\csname STK\the
    \STKcount\string~\endcsname{#1}}
  \def\popnil{\expandafter\let
    \expandafter\temp@macro\csname
     STK\the\STKcount\string~\endcsname
    \ifnum\STKcount>0\global\expandafter
      \let\csname STK\the\STKcount
      \string~\endcsname=\undefined@
      \global\advance\STKcount-1%
    \else
      \def\temp@macro{}\global\STKcount=0%
    \fi\relax }
  \def\pop{\popnil\temp@macro}
\unsetraw


The first four lines of code will ensure that the stack pointer
will not be flushed if this useful subset of macros is loaded
again by for instance another style file in the middle of a \TeX
\ document. With the above code, we can stack away anything by
{\tt\string\push$\{anything\}$} and later use {\tt \string\pop}
to recall them or {\tt \string\popnil} to remove one element from
the stack.


\medskip
So, how can we make defaults for certain empty macro
parameters? The simplest case is perhaps


\setraw
  \long\def\get@nepara[#1][#2]{{%
    \def\next@{#2}%
    \ifx\next@\empty\push{#1}\else
    \push{#2}\fi}\ag@in}
  \long\def\get@para\left@#1\right@{%
    \def\check@{%
    \ifx[\next@
    \def\full@####1{\get@nepara[#1]####1}%
    \else
    \def\full@{\get@nepara[#1][#1]}\fi
    \full@}%
  \futurelet\next@\check@}
\unsetraw



Basically, {\tt\string\get@onepara[<A>][<B>]} will push the
default {\tt <A>} to the stack {\tt STK} unless {\tt <B>} is
nonempty. And {\tt\string \get@para\string \left@<A>\string
\right@} will look at the next token to be read, if it is
character \lq{\tt[}\rq, then reads in a macro parameter in the
form of {\tt [<B>]} and then push {\tt <B>} to the stack {\tt
STK}, otherwise push the default {\tt <A>} to that stack. For the
more general case, we need to define


\setraw
  \long\def\do@nepara
    \left@#1\right@#2\p@r@end{%
    \gdef\p@r@data{#2}\global\advance
    \p@r@count1\get@para\left@#1\right@}
  \def\ag@in{\ifx\p@r@data\empty
    \def\next@{\relax\getp@r@s\run@CMD}%
    \else\def\next@{\expandafter\do@nepara
         \p@r@data\p@r@end}%
    \fi\next@}
  \def\run@CMD{\csname STK\the\STKcount
    \string~\endcsname}
  \newcount\p@r@count
  \long\def\st@ckparas#1\p@r@end{%
    \global\p@r@count=0%
    \gdef\p@r@data{#1}\ag@in}
\unsetraw


so that {\tt\string\st@ckparas \string\left@<A>\string\right@
...\penalty -20 \string\left@<B>\string\right@ ...
\string\p@r@end} will look for parameters enclosed in {\tt []}
one by one, exhausting all the defaults paired by
{\tt\string\left@} and {\tt \string\right@}. If future tokens
inside {\tt []} are not found, or empty, the default tokens
inside the corresponding pair {\tt\string\left@ \string\right@}
will be used. The new or default tokens will be pushed to the
general-purpose stack {\tt STK} for a later use, while {\tt
\string\p@r@count} records the total number of the default macro
parameters. We note that on exit of {\tt \string\st@ckparas}, the
control is passed to {\tt\string\runCMD}.

\medskip
Once all macro parameters are pushed to the stack, we may
transfer them to separate toks {\tt \string\p@r@one} to {\tt
\string\p@r@nine} (an easier-to-use format) defined by

\setraw
  \newtoks\p@r@one\newtoks\p@r@two
  \newtoks\p@r@three\newtoks\p@r@four
  \newtoks\p@r@five \newtoks\p@r@six
  \newtoks\p@r@seven\newtoks\p@r@eight
  \newtoks\p@r@nine
  \def\clrp@r@s{\global\p@r@one={}%
   \global\p@r@two={}\global\p@r@three={}%
   \global\p@r@four={}\global\p@r@five={}%
   \global\p@r@six={}\global\p@r@seven={}%
   \global\p@r@eight={}\global\p@r@nine={}}
\unsetraw

where {\tt\string\clrp@r@s} clears all the parameter toks. We can
then retrieve parameters from the stack {\tt STK} to the
parameter toks via {\tt\string \getp@r@s} with the following code


\setraw
  \newcount\temp@count
  \def\getp@r@s{\temp@count=\p@r@count
  {\loop
   \ifnum\temp@count>0
   \expandafter\let\expandafter
   \t@macro\csname STK\the\STKcount
     \string~\endcsname
   \ifcase\temp@count
   \or\global\p@r@one=\expandafter{\t@macro}%
   \or\global\p@r@two=\expandafter{\t@macro}%
   \or\global\p@r@three=\expandafter{\t@macro}%
   \or\global\p@r@four=\expandafter{\t@macro}%
   \or\global\p@r@five=\expandafter{\t@macro}%
   \or\global\p@r@six=\expandafter{\t@macro}%
   \or\global\p@r@seven=\expandafter{\t@macro}%
   \or\global\p@r@eight=\expandafter{\t@macro}%
   \or\global\p@r@nine=\expandafter{\t@macro}%
   \else
    \errmessage
    {Parameter capacity exceeded.}%
   \fi \global\expandafter\let
   \csname STK\the\STKcount
   \string~\endcsname=\undefined@%
   \global\advance\STKcount-1%
   \global\advance\temp@count-1\relax
   \fi
   \ifnum\temp@count>0\repeat}}
\unsetraw



\medskip
We are now ready to use the above mechanism to default
macro parameters for some already defined macros. Suppose we have
already defined a macro {\tt \string\crudemac[<A>][<B>]} which
takes two macro parameters {\tt <A>} and {\tt<B>}, and we want to
define a new macro {\tt \string\smartmac} which behaves like {\tt
\string\crudemac} but will default the macro parameters {\tt <A>}
and {\tt <B>} to for instance 9 and 88 respectively. For this
purpose, we may define {\tt \string\smartmac} via



\setraw
  \def\smartmac{\push{%
   \edef\next@@{\noexpand
   \crudemac[\the\p@r@one][\the\p@r@two]}%
   \popnil\clrp@r@s\next@@}\st@ckparas
   \left@9\right@\left@88\right@\p@r@end}
\unsetraw

This way, all the followings

\setraw
  \crudemac[9][88], \smartmac[9][88],
  \smartmac, \smartmac[], \smartmac[][],
  \smartmac[9], \smartmac[9][], \smartmac[][88]
\unsetraw

are the same under the assumption that we shall not use
characters \lq{\tt[}\rqs and \lq{\tt]}\rqs for the macro
parameters themselves, and that {\tt\string\crudemac} will not
change any {\tt \string\catcode} inside. The reason for this
latter condition lies in the fact that when {\tt\string\smartmac}
looks at the next character, the character is in a sense already
read. If {\tt \string\crudemac} changes the {\tt\string\catcode}
of that particular character, then the one that is already read
via {\tt\string\futurelet} will have a misleading
{\tt\string\catcode}. If one has to change {\tt \string\catcode}
inside but wants to avoid this possible misbehavior, always put
full number of empty brackets \lq{\tt[]}\rqs for the defaults, or
put a {\tt\string\relax} immediately afterwards. Better still,
make the last parameter to appear in a mandatory \lq$\{\}$\rqs form
rather than the \lq{\tt []}\rqs form via the {\tt \#$\{$} mechanism
[1], so that those square brackets can be dropped off.


\medskip


For example, we as a by-product also defined a 100\%
verbatim mode by

{\stt
\ \ \string\begin@@rawlist[$A$][$B$][$C$][$D$][$E$][$F$]$G$ }\par
\setraw
   <general text>
  \endrawlist
\unsetraw


where, for the line numbering of the raw text, {\tt $A$}, ...,
{\tt $G$} represent respectively the initial value, increment
step, number of digits, font, horizontal position of text,
horizontal shift of numbering, and the password to leave raw text
mode. Incidentally, {\tt \string\linecount} records the current
line numbering count. Our purpose is to define {\tt
\string\beginrawlist} so that its format is

{\stt
\ \ \string\beginrawlist[$A$][$B$][$C$][$D$][$E$][$F$]$\{G\}$}\par

in which $A$ to $F$ are {\sl optional} while $\{G\}$ is mandatory
even though $G$ can be empty --- implying {\tt
\string\endrawlist} is the password to leave the raw-text mode.
For this purpose, we first define

\setraw
\def\begin@rawlist[#1][#2][#3][#4][#5][#6]#{%
    \begin@@rawlist[#1][#2][#3][#4][#5][#6]}%
\unsetraw

to make \lq$\{\}$\rqs pair compulsory for {\tt \#7}, then we
provide the defaults for {\tt $A$} to {$F$} as
{\tt\string\linecount}, {\tt 1}, {\tt 0}, {\tt \string\tiny},
{\tt 0pt} and {\tt 0pt} respectively via

\setraw
\def\beginrawlist{\push{%
 \edef\next@@{\noexpand\begin@rawlist
 [\the\p@r@one][\the\p@r@two][\the\p@r@three]%
 [\the\p@r@four][\the\p@r@five][\the\p@r@six]}%
 \popnil\clrp@r@s\next@@}%  end of push
 \font\tiny@rm=cmr5%
 \edef\temp@macro{%
  \noexpand\left@\the\linecount\noexpand\right@
  \noexpand\left@1\noexpand\right@
  \noexpand\left@0\noexpand\right@
  \noexpand\left@\noexpand\tiny@rm
           \noexpand\right@
  \noexpand\left@0pt\noexpand\right@
  \noexpand\left@0pt\noexpand\right@}%
  \expandafter\st@ckparas\temp@macro\p@r@end}%
\unsetraw

\medskip

{\smooth
\relax Likewise, we could also similarly define {\tt \string\printfile
[...]}$\{${\it filename.ext}$\}$ so that \lq{\tt [...]}\rqs takes
a same defaulting scheme. }


\medskip
There are several tiny but very useful macros in {\tt formlett}
which are used again and again. One of such macros is for testing
if one string contains another string. The following {\tt
\string\test@str} tests if string {\tt\#1} is contained in string
{\tt\#2}


\setraw
  \newif\iftemp@if \newtoks\temp@toks
  % return \temp@iftrue if yes,
  %  \first@half,\second@half are global
  \long\def\test@str#1#2{%
    \long\def\strip@endmark##1\s@fetymarkI
      #1\s@fetymark{\gdef\second@half{##1}}%
    \long\def\strip@markI##1\s@fetymarkI
      \s@fetymark{\gdef\first@half{##1}}%
    \long\def\p@rse##1#1##2\s@fetymark{%
      \gdef\first@half{##1}%
      \gdef\second@half{##2}%
      \ifx\second@half\empty
       \strip@markI##1\s@fetymark\temp@iffalse
      \else
       \strip@endmark##2\s@fetymark\temp@iftrue
      \fi}%
    \temp@toks={#2\s@fetymarkI#1\s@fetymark}%
    \expandafter\p@rse\the\temp@toks }%
\unsetraw


The {\tt\string\first@half} will contain the tokens upto but
excluding the substring {\tt\#1}, while the {\tt
\string\second@half} will contain the tokens after the {\sl
first} appearance of {\tt\#1}. Should {\tt\#2} not contain string
{\tt\#1} at all, then {\tt \string\first@half} is the whole
string {\tt\#2} whereas {\tt \string\second@half} is empty.

\medskip

The small macros such as the above one and the stack utilities,
though built for the main purpose of {\tt formlett}, provide also
a good \lq infrastructure\rqs for other house-keepings. One of
the sidekicks of this type is our macro for commenting out blocks
of text inside a \TeX\ file. Basically, {\tt
\string\begincomment$\{$\it password$\}$} will set {\sl all}
characters of code {\tt0} to {\tt \string\MAX@CHR@CODE}
(={\tt255} by default) to catcode 11 or 12, and look for the {\it
password}, or {\tt \string\endcomment} in the absence of a
password, to quit the comment mode. In comparison to a very
compact macro {\tt comment.sty} (currently at version 3.0)
written by Victor Eijkhout, quitting comment mode via a password
here seems more flexible.




\medskip
As for the other macros in {\tt formlett}, it is difficult to
explain them without printing out all of them. So instead, we
shall explain simply one of the strategies in parsing the letter
parameters. Suppose $W$ is a list of parameters separated by
\lq{\tt+}\rqs and ended by \lq{\tt!}\rq, i.e. $W$ is like
{\tt<A>+<B>+...+<S>!}. Then it will be easy to parse all the
parameters one by one (to a stack for instance) if we can know
whether there is precisely one parameter left over. To detect it,
we use



\setraw
  \newif\ifl@stline
  \long\def\testl@stline
    #1+#2!#3\s@fetymark{%
   \def\next{#2}\ifx\next\empty
   \l@stlinetrue\else\l@stlinefalse\fi
   \def\next{#3}\def\nextsample{+!}%
   \ifx\next\nextsample\l@stlinefalse\fi}
\unsetraw



{\smooth Then the command
{\tt \string\testl@stline} {\tt $W$+!\string\s@fetymark }
will set {\tt \string\l@stlinetrue} if
there is only one parameter left in $W$, and will set {\tt
\string\l@stlinefalse} if otherwise. }



\medskip

Finally, for those wizard users who want to do everything their own way,
we just note that if for instance the 3rd letter parameter of the 2nd
group of a cluster is given as {\tt<A>}, then {\tt \string\LET2*3\t}
will contain {\tt \string\b@group \string\relax {\tt<A>}\string\e@group}
right after a cluster is read in. {\tt \string\DEF2*3\string~}, on the
other hand, contains the corresponding default parameter in the same
fashion. Furthermore, the command
{\tt\string\checkparas[$m$][$n$]$\{$LET$\}$} will copy the content of
{\tt\string\paras[$m$][$n$]}, minus the `wrapping' extra tokens
{\tt\string\b@group\string\relax} and {\tt\string\e@group}, to
{\tt\string\cachedata} and set {\tt\string\ifemptyparas} to true or
false depending on whether the content is empty or not. This way, a user
may even change the characteristics of his letter template by first
testing the content of the supplied individual parameters. However, we
note that if {\tt\string \loaddefaultparas} is executed, then the {\tt
LET} array, when some of its elements are not supplied, will contain the
corresponding elements of the {\tt DEF} array. Hence care must be
exercised under such circumstances, when interpreting the
{\tt\string\cachedata} generated by
{\tt\string\checkparas[$m$][$n$]$\{$LET$\}$}. If necessary, we may use
{\tt\string\delparadefaults} to delete current default parameter array
{\tt DEF} so as to conduct {\tt\string\checkparas$\{$LET$\}$} more
precisely. So if anyone wants to manipulate furthermore letter
parameters inside a letter template, he or she will now at least know
where to look at.

%\penalty -50
\bigskip
{\lbold References}

\smallskip
{\parindent=2em
\item{[1].} Knuth D E, {\sl The \TeX book}, Reading, Mass.,
Addison-Wesley, 1992. \par
\item{[2].} Piff M, Text merges in \TeX\ and \LaTeX, {\sl TUGboad},
13(4):518, 1993. \par
\item{[3].} Damrau J and Wester M, Form letters with 3-across
labels capacity, {\sl TUGboat}, 13(4):510, 1991.
\par
}


\penalty -50\bigskip

{\lbold Appendix}


\smallskip


In the followings, we give a brief summary of the new commands
given by {\tt formlett} version 2.3.

\medskip

Let $m$ and $n$ be numbers, $p$, $q$ and $r$ be dimensions, $A$,
$B$, $P$, $G$, $C$ and $T$ be tokens, and $X$ be a box.
Furthermore, we shall denote by $R$ a full set of letter
parameters ended by \lq{\tt !}\rq, with \lq{\tt;}\rqs separating
parameters inside a same group and \lq{\tt+}\rqs separating
different parameter groups. We moreover denote $R$ by $F$, when
\lq{\tt ; + !}\rqs there can be replaced by \lq$P$ $G$ $C$\rqs
respectively if {\tt \string\delimiters$\{P\}\{G\}\{C\}$} is
issued. In the commands tabulated below, the macro parameters
contained in squared brackets support default. In particular, the
defaults are $m$={\tt 1}, $n$={\tt 1}, $p$={\tt 8truecm},
$q$={\tt 1.5em}, $r$={\tt 3pt}, $A$={\tt\string\noindent},
$B$={\tt\string\par}, {\tt\string\previewfalse},
{\tt\string\localparastrue} and {\tt\string\nodefaultsfalse}.


%\penalty-10000

\vskip 0pt plus 5cm


\newdimen\tempdimone
\newdimen\tempdimtwo
\tempdimone=\hsize
\advance\tempdimone by-0.2pt
\tempdimtwo=\hsize
\advance\tempdimtwo by-1.8in
\def\hruler{\hrule width \tempdimone}
\long\def\entry#1#2{%
\par\hbox to \tempdimone{\noindent
       \vrule~\textbox[1.7in]{#1}~\hss
       \vrule~\textbox[\tempdimtwo]{\raggedright#2}~\vrule}%
       \par}

\long\def\longentry#1#2#3{%
\par\hbox to \tempdimone{\noindent
       \vrule~\textbox[3in]{#1}~\hss~\vrule}\par
        {\kern-8pt \advance\tempdimtwo0.10in
         \vrule width1.7in height0pt \vrule width\tempdimtwo height 0.4pt \par
         \kern-3pt}
        \entry{#2}{#3}}

\long\def\Longentry#1#2#3{%
\par\hbox to \tempdimone{\noindent
       \vrule~\textbox[3in]{#1}~\hss~\vrule}\par
       {\advance\tempdimtwo0.08in\kern-1pt
        \vrule~\hfill\vrule width \tempdimtwo height 0.4pt \vrule\par
        \kern-2.5pt}%
        \entry{#2}{#3}}



\medskip \penalty-100
{\eightpoint
\nointerlineskip\parskip=0pt

\hruler
\entry{{\tt\string\paras[$m$][$n$]}}%
  {$m^{th}$ parameter of $n^{th}$ group }%

\entry{{\tt\string\blockparas[$m$][$n$][$A$][$B$]}}%
  {$m^{th}$ to the last parameter of $n^{th}$ group, each
preceded by $A$ and followed by $B$, wrapped by $\{$\penalty
1000$\}$ if
$B$={\tt\string\relax}}

\entry{{\tt\string\addressparas[$m$][$n$][$p$][$q$]}}%
  {$m^{th}$ to the last parameter of $n^{th}$ group, each put
into a box of width $p$ with indent $q$ for wrapped portions}


\entry{{\tt\string\loaddefaultparas}}%
  {fill empty parameters with defaults}

\hruler \penalty-1000
\hruler


\entry{{\tt\string\checkparas[$m$][$n$]$\{T\}$}}%
  {$m^{th}$ parameter of $n^{th}$ group copied to {\tt\string\cachedata};
   {\tt\string\ifemptyparas} is true if element is empty; $T$ is often
   {\tt LET} or {\tt DEF}}%

\hruler


\entry{{\tt\string\moreletter\ $F$}}%
  {use parameters $F$ to output a new letter}


\entry{{\tt\string\paranames\ $R$}}%
  {use $R$ as parameter names}

\entry{{\tt\string\paradefaults\ $R$}}%
  {use $R$ as default parameters}


\entry{{\tt\string\delparadefaults}}%
  {delete default parameters}

%\hruler \penalty-1000
\hruler


\entry{{\tt\string\delimiters$\{P\}\{G\}\{C\}$}}%
  {use $P$, $G$, $C$ as delimiters}


\entry{{\tt\string\defaultmarks}}%
  {use \lq{\tt ; + !}\rqs as delimiters}


\entry{{\tt\string\blockmarks}}%
  {use \lq{\tt ....}\rq, \lq{\tt ----}\rq, \lq{\tt ====}\rqs as delimiters}

%\hruler \penalty -1000
\hruler

\entry{{\tt\string\preview}}%
  {highlight parameter positions}

\entry{{\tt\string\showparas}}%
  {display parameter names, if any}

\entry{{\tt\string\inputletter$\{file.ext\}$}}%
  {input letter content}

\entry{{\tt\string\inputfile$\{file.ext\}$}}%
  {input $file.ext$}

%\hruler \penalty -1000
\hruler


\entry{%
$\left\{\matrix{ \hbox{\tt\string\beginletter}\cr
\hbox{\tt\string\endletter~~}\cr}\right.$ }%
  {delimiters for letter content (template)}

\entry{%
$\left\{\matrix{ \hbox{\tt\string\beginpilemode}\cr
\hbox{\tt\string\endpilemode~~}\cr}\right.$ }%
  {normal letter parameters cluster-wise}


\entry{%
$\left\{\matrix{ \hbox{\tt\string\beginblockmode}\cr
\hbox{\tt\string\endblockmode~~}\cr}\right.$ }%
  {for line-by-line blocks of parameters, empty lines active
within each cluster}


\entry{%
$\left\{\matrix{ \hbox{\tt\string\beginlinemode}\cr
\hbox{\tt\string\endlinemode~~}\cr}\right.$ }%
  {for line-by-line parameters, empty lines delimit clusters}

%\hruler \penalty-1000
\hruler

\entry{%
$\left\{\matrix{ \hbox{\tt\string\beginrawblockmode$\{T\}$}\cr
\hbox{\tt\string\endrawblockmode\ \ \ \ \ }\cr}\right.$ }%
  {raw text mode; nonempty $T$ replaces {\tt\string\endrawblockmode}
   to mark end}


\entry{%
$\left\{\matrix{ \hbox{\tt\string\beginrawlinemode$\{T\}$}\cr
\hbox{\tt\string\endrawlinemode\ \ \ \ \ \ }\cr}\right.$ }%
  {raw text parameters and active spaces etc}

\entry{%
$\left\{\matrix{ \hbox{\tt\string\begindatamode[$T$]$\{m\}$}\cr
\hbox{\tt\string\enddatamode\ \ \ \ \ \ \ \ }\cr}\right.$ }%
  {$m$ raw text lines for one form letter}

\hruler

\entry{%
$\left\{\matrix{ \hbox{\tt\string\begincolumns[$a$][$b$]}\cr
\hbox{\tt\string\endcolumns\ \ \ \ \ \ \ }\cr}\right.$ }%
  {$a$-columns separated by distance $b$}


\entry{%
$\left\{\matrix{ \hbox{\tt\string\begincomment$\{T\}$}\cr
\hbox{\tt\string\endcomment\ \ \ \ \ }\cr}\right.$\par
 \ \ \ {\tiny }}%
  {comment out lines, nonempty $T$ replaces {\tt
\string\endcomment} to mark last {\sl full line} for comment}


\entry{%
$\left\{\matrix{ \hbox{\tt\string\beginfile[$T$]$\{{\it
file.ext}\}$}\cr
\hbox{\tt\string\endfile\ \ \ \ \ \ \ \ \ \ \ \ \ }\cr}\right.$\par
 \ \ \ {\tiny }}%
  {write text verbatim to file {\it file.ext} (empty implies {\tt
scr@tch@.tex}), nonempty $T$ replaces {\tt
\string\endfile} to mark last full line}



\hruler


\entry{{\tt\string\PAGENO=1}}%
  {page number reset to 1}


\entry{{\tt\string\NOPAGENUMBERS}}%
  {no page numbers}


\entry{{\tt\string\textbox[$p$]$\{text\}$}}%
  {$text$ into box of width $p$}


\entry{{\tt\string\boxmore[$r$]$\{X\}$}}%
  {add borderline to box $X$ at a distance $r$}


\entry{{\tt\string\addressbox[$p$][$q$]$\{text\}$}}%
  {$text$ into box of width $p$, with wrapped options indented
by $q$}

\hruler


\entry{{\tt\string\previewfalse}}%
  {given parameters instead of highlighted boxes will be shown}


\entry{{\tt\string\localparastrue}}%
  {letter parameters put into $\{\}$ before displayed}


\entry{{\tt\string\nodefaultsfalse}}%
  {take defaults for empty letter parameters}

\hruler

\entry{{\tt\string\previewtrue}}{{\it cf.} above}


\entry{{\tt\string\localparasfalse}}{}


\entry{{\tt\string\nodefaultstrue}}{}

\hruler

\vskip0pt plus 1cm
~\hfill $\underline{\hbox{\sl Table continues in the next page}}$

\penalty-5000
\hruler


\Longentry{%
$\left\{\matrix{ \hbox{\tt\string\beginrawlist
       [$a$][$b$][$c$][$d$][$e$][$f$]$\{g\}$}\cr
 \hbox{\tt\string\endrawlist\hskip3.4cm}\cr}\right.$ }%
 {\strut\par{\sl defaults:}\everypar={\hbox{\ \ \ }}\par\par
  $a$={\tt\string\linecount},\par
  $b$={\tt1}, $c$={\tt0},\par
  $d$={\tt\string\tiny@rm}, \par
  $e$={\tt0pt},  $f$={\tt0pt}, \par
  $g$={\tt\string\endrawlist}}%
{verbatim listing, line count from $a$, step $b$, digits $c$,
font $d$, text position $e$, numbering shift $f$, end mark $g$}

\hruler \vskip0.5pt
\Longentry{%
$\matrix{\hbox{\tt \string\printfile
       [$a$][$b$][$c$][$d$][$e$][$f$]$\{$\it file.ext$\}$}\cr
 \hbox{}\cr}$}%
  {\strut\par{\sl defaults:} ~~$c$={\tt6} {\it etc}}%
      {verbatim listing of {\it file.ext}}

\hruler



\Longentry{%
$\left\{\matrix{ \hbox{\tt\string\beginlabels
       [$a$][$b$][$c$][$d$][$e$][$f$]}\cr
 \hbox{\tt\string\endlabels\hskip3cm}\cr}\right.$ }%
 {\strut\par{\sl defaults:}\everypar={\hbox{\ \ \ }}\par\par
  $a$={\tt 20pt}, \par $b$={\tt\string\tt\string\raggedright},
 \par $c$={\tt1}, $d$={\tt1}, \par
  $e$={\tt2.6in},  $f$={\tt2em}}%
 {form letters become labels: address taken from $c^{th}$ to
last parameter of $d^{th}$ group, with width $e$, indent
$f$, borderspace $a$ and font toks $b$}

\hruler


\entry{{\tt\string\firstread$\{T\}$}}%
  {toks $T$ will not be read if the file is re-read via {\tt
   \string\labelsquit}}


\entry{{\tt\string\initstyle[$a$]$\{b\}\{c\}$}}%
  {initiation for {\tt\string\labelsquit},with styles $a$,
   documentstyle $b$ and preamble $c$}

\entry{{\tt\string\initclass[$a$][$o$]$\{b\}\{c\}$}}%
  {similar to {\tt\string\initstyle} ($o$ is \LaTeX2e options),
   but retains  native \LaTeX2e when applicable}


\hruler \vskip0.5pt
\Longentry{%
$\matrix{\hbox{\tt \string\labelsquit
       [$a$][$b$][$c$][$d$][$e$][$f$]$\{$\it file.ext$\}$}\cr
 \hbox{}\cr}$}%
 {\strut\par{\sl defaults:}\everypar={\hbox{\ \ \ }}\par\par
  see that for {\tt\string\beginlabels}}
  {quit after converting letters to labels by reading the current
   document or {\it file.ext}}

\hruler



\def\ABC{{\tt\esc@}{\it abc}}


\entry{{\tt\string\newarray\ABC}}%
  {make array named {\it abc} along with
   {\tt\ABC} and {\tt\string\check{\it abc}}}


\entry{{\tt\string\delarray\ABC}}%
  {delete array named {\it abc}}


\hruler


\entry{{\tt\ABC($m$)=$\{T\}$}}%
   {assign tokens $T$ to {\tt\ABC($m$)};
    {\tt\ABC($m$)} $\equiv$
    {\tt\ABC($m_1,...,m_k$)} for
    $m$=$1+\sum_1^k  (m_i-1)*\hbox{\tt\string\dataheight}^{k-i}$}


\entry{{\tt\ABC($m$)}}{value of {\tt\ABC($m$)},
       if not followed by `{\tt=}'}


\entry{{\tt\string\dataheight}}{current array dimension: {\it cf.}
       {\tt\ABC($m$)}}


\entry{{\tt\string\readarray$\{N\}\{a_1 \hbox{\&}\, ..\, \hbox{\&} a_n\}$}}%
   {equivalent to {\tt\esc@{\it N}(1)}=$a_1$, ..,
   {\tt\esc@{\it N}($n$)}=$a_n$}



\entry{{\tt\string\check{\it abc}($m$)}}%
      {copy {\tt\ABC($m$)} to {\tt\string\cachedata};
       set {\tt\string\ifemptydata} to true/false accordingly}


\hruler

\entry{{\tt\string\readstyles$\{f_1,...,f_n\}$}}%
      {read files $f_1$ to $f_n$ with default extension {\tt .sty};
       {\tt @}'s catcode set to {\tt 11} during input}

\hruler


}

\footline={\lower5pt
\hbox to \hsize
 {{\rm Jiang Z ~~~{\sl Formlett: ~for letters to multiple receivers}
  \hss {\sl $\bullet$End of Document$\bullet$}
\hss \folio}}}

\vskip 8in

%\vfill\eject
\endcolumns
\vfill\eject



%%%%%%%%%%%%%%%%%%
% MAKE EXAMPLE1.TEX EXAMPLE2.TEX
%%%%%%%%%%%%%%%%%%



\message{Can I create <example1.tex> and <example2.tex> ? (y/n) }%
\read-1 to \reply \def\nono{n }\def\Nono{N }\def\noNo{no }\def\NoNo{NO }%
\def\next{\end{document}}%
\ifx\reply\nono\else\ifx\reply\Nono\else\ifx\reply\noNo\else
\ifx\reply\NoNo\else\let\next\relax
\message{(=== YES ===)}\fi\fi\fi\fi \next




\beginfile[EndOfExample1]{example1.tex}

% Example1: EXAMPLE for using scratch files
%           under plain TeX or LaTeX
%

\input formlett.sty
%
%%%%  MAKE scr@tch@.let
%
\beginfile{scr@tch@.let}

% letter content
\boxmore[10pt]{\hbox{\vbox{%  BOX FOR BORDERLINE

\parindent=0pt
\blockparas

\bigskip\bigskip

Dear \paras,

\bigskip

This part is typically the letter content. Since we are using a
scratch file for our main body of our letter, the letter can be
arbitrarily long, in comparison to using {\tt \string\beginletter}
and {\tt \string\endletter} mechanism. Using a scratch file enables
us to keep everything inside one single file so that it won't be mixed
up with other letters.

\medskip

The idea of scratch file can also be applied to creating the address
file, so that the address file can be read for the form letters in the
first time and for mailing labels in the second time. These features are
the purpose of this particular example.

\medskip
Thanks for using {\tt formlett.sty}.

}}}  % END OF BOX FOR BORDERLINE
\vfill\eject

\endfile


%
%%%%  MAKE scr@tch@.adr
%
\beginfile{scr@tch@.adr}
% address file
\beginlinemode
\tt<name>
address line one
address line two
etc

\tt<NAME>
ADDRESS LINE ONE
ADDRESS LINE TWO
ETC

\endlinemode
\endfile


%
%%%  MAIN PROCESSING BODY
%

\hsize=5in
\initstyle{}{}
       % Above line is put here for being
       % able to run this file under either TeX or LaTeX.
       % It may be deleted for TeX. It may also be replaced
       % under LaTeX by  \documentstyle{article} \begin{article}
       % for instance

\inputletter{scr@tch@.let}
\inputfile{scr@tch@.adr}  % for form letters
\beginlabels
\inputfile{scr@tch@.adr}  % for labels
\endlabels

\end{document}

EndOfExample1
% above is password






\beginfile{example2.tex}%

% Example2: EXAMPLE for self-read
%           under plain TeX or LaTeX
%


\input formlett.sty
\hsize=3.2in  % for plain TeX
\initstyle[]{}{\textwidth=3.2in}  % for LaTeX

% MY LOGO
%
\catcode`\@=11\relax
\def\UWS{{\vbadness=10000 \hbadness=10000 \hfuzz=\maxdimen
  \vfuzz=\maxdimen  \font\tiny=cmr5 \font\small=cmr7
  \def\today{\number\day\space\ifcase\month\or January\or February\or
      March\or April\or May\or June\or July\or August\or September\or
      October\or November\or December\fi\space\number\year}%
  \def\make@temp@box{\csname newbox\endcsname \temp@box\relax}%
  \ifx\temp@box\undefined \def\next{\make@temp@box}\else\def\next{}\fi\next
  \font\HUGE=cmss10 at  24.87999pt \noindent
  \setbox\temp@box=\hbox{\vbox to 0pt{\hbox{\HUGE
          U\hskip6pt W\hskip6pt S}}}%
  \def\buffdim{65pt}%\wd\temp@box  61.588pt
  \rlap{\copy\temp@box}%
  \rlap{\hskip.4pt\copy\temp@box}%
  \rlap{\hskip.8pt\copy\temp@box}%
  \rlap{\hskip1.2pt\copy\temp@box}%
  \rlap{\hskip1.6pt\copy\temp@box}%
  \rlap{\hskip2pt\copy\temp@box}%
  \rlap{\hskip2.4pt\copy\temp@box}%
  \rlap{\hskip2.8pt\copy\temp@box}%
  \rlap{\hskip6pt\copy\temp@box}%
  \rlap{\lower23pt \hbox to \buffdim{\tiny \hskip4pt The ~~~University~~~ Of}}%
  \rlap{\lower25pt \hbox{\hskip2pt
         \hbox to \buffdim{\vrule width \buffdim depth .2pt}}}%
  \rlap{\lower32pt \hbox to \buffdim{\small \hskip-1pt WESTERN SYDNEY}}%
  \setbox\temp@box=\hbox{\vbox{\let\noindent=\hfill
    \font\small=cmss8 \baselineskip=8pt %plus 0.5pt minus 0.5pt
    \small \parskip=0pt
    \noindent School of Computing and IT\par
    \noindent University of Western Sydney\par
    \noindent Victoria Road, Parramatta\par
    \noindent NSW 2150, Australia\par
    \medskip
    \noindent Email: ~z.jiang@uws.edu.au\par
    \noindent Tel: ~(INT-) 61- 2- 96859336\par
    \noindent Fax: ~(INT-) 61- 2- 96859245\par
    \medskip\bigskip
    \noindent \tt\today}}%
   \rlap{\lower3.0cm \hbox{\box\temp@box}}%
}\par}\catcode`\@=12\relax
%

\beginletter
\paranames             % optional
  \tt<<FULL NAME>>;%
  \tt<<ADDRESS-etc>>;%
 +\tt<<GIVEN NAME>>;%
  \tt<<MISSING ITEM>>;%
  \tt<<PHONE NUMBER>>!
\loaddefaultparas      % optional

\NOPAGENUMBERS\parindent=0pt\overfullrule=0pt
\UWS \par\bigskip\bigskip\bigskip
\noindent{\it\paras[1]}\par
\blockparas[2]\par\bigskip

Dear \paras[1][2],\par\medskip
We have been looking for
\paras[2][2] for quite a while
without any luck, could you help
us out? If so, please ring
\paras[3][2]. \par\medskip
Cheers!\hfill Zhuhan\vfill\eject
\endletter
\preview \showparas
\eject  % \eject here is purely for better labels


\paradefaults       % optional
  To whom this may concern
 +Sir or Madam;something;%
  061-225-9905!


\blockmarks
\beginblockmode

Mrs L Stenson
\#1-20 Sunset Street
Hillside, Norway
------                           separate groups
Louise
a Bible
220-8888
=========                        separate cluster

......                           force entry next line

Above empty line active

\endblockmode                 comment ignored

\defaultmarks
\moreletter
   S Wales,;%
   \addressbox[2in][1em]{University of Manchester Institute
   of Science and Technology, This is
   a long address line: it will be
   wrapped up automatically.}
 +;a \TeX\ package \gstr\ manual and
   many more (\cstr)!

\beginlinemode
  S Pan
  UNE, Arimdale

  T Ribbons
  UMIST, Manchester
\endlinemode

\beginpilemode

  C Anderson;42nd Street;USA+Christine;your service invoice!

  D Holmes;Flat \#2, Finneybank Rd;London+David;the tax receipt;%
     071-902 7799!

\endpilemode

\begindatamode{3} % strictly 3 lines for one letter
data-#1
data-#2
data-#3
data-#4
data-#5
\enddatamode

\ifISLATEX \firstread{\global\textwidth=6in}
\else \firstread{\hsize=6in}\fi  % make labels double columns

\labelsquit{}
\end{document}  % redundant
\endfile



\message{Now go and TeX or LaTeX <example1.tex> and <example2.tex>}%


\end{document}
%
%
%
%ENDDOCUMENT