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C00002 00002	% copyright 1984 by Arthur Keller ... All rights reserved
C00005 00003	\section*{Assignment}
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% copyright 1984 by Arthur Keller ... All rights reserved
\chapter{Breaking lines into pages}

%Fri, August 24

%11am-12n
%Breaking lines into pages
%>Penalties
%>Insertions and ``floating'' insertions
%>What page are we on?
%>A little about output routines

%1-2pm
%<lab assignment 13>

The page-breaking routine, by which \TeX\ breaks lines of typeset text
into pages, is even more complicated than the line-breaking routine.
The important thing to know is that \TeX\ takes successive \cmd{hbox}es,
each containing a line of output, and places them on the page to make up
what is known as the {\sl main vertical list}.
Eventually enough accumulate for \TeX\ to decide to start a new page.

Each \cmd{hbox} containing a line of text has a height equal to the height
of the tallest ascending character, a depth equal to the depth of the
lowest descending character, and a width equal to the natural width of the
page (unless another width was specified).
Thus a line of text consisting of all o's, m's, etc., would have zero depth
(no descenders) and a smaller height than a line of text which included
l's, d's, etc.
If \TeX\ were then to place the boxes vertically, separating the bottom of
one box from the top of the next by a {\sl fixed} amount of glue, the
resulting baselines of the characters would be closer together or farther
apart depending on the contents of the boxes.
Two lines of o's would appear much closer together than would a line of
y's followed by a line of l's.

However, in order to have good-looking output, we want the distance
between the {\sl baselines} of successive lines (rather than the amount of
glue between successive boxes) to be constant.
This is why space between lines is specified in terms of the amount of
\cmd{baselineskip} rather than in terms of the amount of glue between
boxes.

\section*{Assignment}

Reading for this lecture:
The {\sl \TeX book}, Chapter~15.

Assignment for this lecture:
The file {\tt texinputs:lab13.tex} contains some paragraphs of friendly
help from the phone company; you should typeset them so that their titles
cannot break between pages.
That is, the first line of the title should not be at the end of a page,
and the next line of the title at the beginning of another next page;
instead, both lines should be on the next page.
You should also change \TeX's parameters so that paragraphs will never
break in the middle, only in between.

You should copy this file to your directory ({\tt @copy texinputs:lab13.tex}).
You will need to add additional commands to the top of the file to
prevent inappropriate page breaking.
And you will need to change the definition of \cmd{title}.

The file {\tt texinputs:lab13.tex} is listed on the next page.

\begin{figure}[p]
\vskip6truein
\caption{Put {\tt texinputs:lab13.tex} here}
\end{figure}