% This file is part of the CTAN package named plain-grid.
% 
%   plain-grid-doc.tex: instructions for the package
%   Version 1.0, 05.05.2026
%
%   Copyright (C) 2026  Udo Wermuth (author)
%
%   This program 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.
%
%   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
%
\def\plaingridversion{1.0}\def\plaingriddate{05.05.2026}
% %%%%%
\hsize=36pc

\input plaingridB.tex
\def\gridlog{ 3 }
% %%%
% %%% verbatim macros (from manmac.tex)
% %%%
\newskip\ttglue {\tt\global\ttglue=0.5em plus 0.25em minus 0.15em }
\def\ttverbatim{\begingroup \frenchspacing
  \catcode`\\=12 \catcode`\{=12 \catcode`\}=12 \catcode`\$=12 \catcode`\&=12
  \catcode`\#=12 \catcode`\%=12 \catcode`\~=12 \catcode`\_=12 \catcode`\^=12
  \obeyspaces \obeylines \tt}
\def\verbatimspace{\ifvmode\indent\fi\space}
{\obeyspaces \gdef\makespaceverbspace{\def {\verbatimspace}}}
\outer\def\verbatim{$$\ifdim\parskip>0pt
    \abovedisplayskip=\parskip \abovedisplayshortskip=\parskip
    \belowdisplayskip=\parskip \belowdisplayshortskip=\parskip
  \else
    \abovedisplayskip=3pt \abovedisplayshortskip=3pt
    \belowdisplayskip=3pt \belowdisplayshortskip=3pt
  \fi
  \let\par=\endgraf \ttverbatim \makespaceverbspace \parskip=0pt
  \catcode`\§=0 \advance\leftskip by 10pt \ttfinish}
{\catcode`\§=0 §catcode`§\=12 % § is temporary escape character
  §obeylines % end of line is active
  §gdef§ttfinish#1^^M#2\endverbatim{§vbox{#2}§endgroup$$}}
\catcode`\|=\active
{\obeylines \gdef|{\ttverbatim \spaceskip\ttglue \let^^M=\  \let|=\endgroup}}

% %%%
% %%% own settings
% %%%
\hyphenation{plaingridT plaingridM plaingridI plaingridB plaingridX
 end-note end-notes endnotesi endnotesii}
\def\alt{\ $\vert$ } \def\<#1>{$<$\hbox{#1}$>$}

% %%%
% %%% code from The \TeX book, page 257
% %%%
\def\plaingridlnostartpage{99 }% later changed
\newdimen\fullhsize
\fullhsize=1.08\hsize \hsize=.475\fullhsize
\def\fullline{\hbox to\fullhsize}
\catcode`@=11
\def\makeheadline{\vbox to\z@{\vskip-22.5\p@
  \fullline{\vbox to8.5\p@{}\the\headline}\vss}\nointerlineskip}
\def\makefootline{\baselineskip24\p@\lineskiplimit\z@\fullline{\the\footline}}
\catcode`@=12
\let\lr=L \newbox\leftcolumn
\output={\if L\lr
    \global\setbox\leftcolumn=\columnbox \global\let\lr=R
  \else \doubleformat \global\let\lr=L\fi
  \ifnum\outputpenalty>-20000 \else\dosupereject\fi}
\def\doubleformat{\shipout\vbox{\makeheadline
    \fullline{\box\leftcolumn\hfil\columnbox}
    \makefootline}
  \advancepageno}
\def\columnbox{\leftline{\pagebody}}

% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\font\titlefont=cmssdc10 at 36pt
\font\subtitlefont=cmssdc10 at 17pt
%
\gridtopinsert \hsize=\fullhsize \null
\centerline{\titlefont plain-grid}
\gridskiponeline \gridsnaptonextbaseline % fix for the unusal font size
\centerline{\subtitlefont Version \plaingridversion, \plaingriddate}
\gridskiponeline \gridsnaptonextbaseline % ditto
\centerline{Macros for plain \TeX\ by Udo Wermuth}
\gridskiponeline
\gridendinsert
\gridskiponeline
% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %%% \headline is set on second page; see start of section 3 below

\noindent
This package contains macros to typeset straight text with a fix
distance between the lines, i.e., the text obeys a baseline
grid. Moreover, the package contains macros to handle displayed
equations, formulas with unusual height and depth in inline
mathematics, vertical boxes, topinserts, and footnotes.

However, the baseline grid is only obeyed if the author avoids all
plain \TeX\ commands that destroy this grid. Therefore, an author must
not use vertical skips, i.e., |\vskip| as well as |\smallskip|, etc.,
or |\smallbreak|, etc., and macros that contain such skips like
|\beginsection|.

For additional information and an example see my article in TUGboat
{\bf47}:1 (2026), 119--134.



\gridbeginsection 1. Activation

To activate the plain-grid macros load one of the following four
files after plain \TeX\ via |\input|.

\gridskiponeline
\item{1.}{\tt plaingridT.tex} supports an author to typeset straight
         text on a baseline grid. It provides macros for endnotes
         too. It also contains a macro to draw horizontal rules.
\item{2.}{\tt plaingridM.tex} helps an author to typeset text and
         mathematics, like displayed equations and theorems. Moreover,
         texts in vboxes are supported.
\item{3.}{\tt plaingridI.tex} adds to {\tt plaingridM.tex} the treatment
         of insertions and footnotes. It includes the feature of a {\sl
         ragged bottom\/} if an author decides to violate the grid
         structure.
\item{4.}{\tt plaingridB.tex} loads {\tt plaingridI.tex} and contains
         macros for vboxes and vtops in horizontal mode, i.e., in
         paragraphs.
\gridskiponeline

The above files usually implement new macros; they do not replace
existing commands of \TeX\ or macros of plain. But there are a few
exceptions: |\pagebody|, |\pagecontents|, |\vfootnote|, and the
protected macro |\@foot|. The first is changed by {\tt plaingridT.tex}
and is therefore active in all files. The others are changed in {\tt
plaingridI.tex}.

As mentioned above, an author must use the new macros to stay on the
baseline grid. Plain \TeX's macros must only be used in certain
structures like math displays or vertical boxes created by the new
macros. Then plain's macros are protected and the grid is at most
violated inside the structure.\looseness=-1

Moreover, an author should be aware that page breaks might occur at
typographically bad places. For example, club and widow lines are
possible and must be fixed by the author.

% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\gridtopinsert \null \gridskipmax7 \gridendinsert % lower 2nd column
% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\gridskiponeline
The new macros do not work correctly if some parameters of the set-up
do not match with each other before they are loaded. This package
requires that (i)~the natural space of\/ |\baselineskip| equals the
sum of height and depth of\/ |\strutbox| and (ii)~|\maxdepth| and
|\boxmaxdepth| are not smaller than the depth of\/ |\strutbox|. Either
check these requirements before any of the above files is loaded or
input the file {\tt plaingridX.tex} after one of the above files was
input. It reports violations of the stated requirements. Nothing is
fixed; do it yourself before the grid macros are loaded. If you
continue although the values do not match, grid-aware typesetting is
not active. When the extra file does not report any mismatch the file
{\tt plaingridX.tex} is no longer needed.

Of course, plain \TeX\ obeys the requirements.



\gridbeginsection 2. Immediate changes

As soon as one of the four files is input, several \TeX\ parameters
receive new values. Only two parameter changes are shown to the user
on the terminal: (a)~A change to the value of\/ |\vsize| and (b)~a
change to the value of\/ |\baselineskip|.

\gridskiponeline
\item{1.}{\tt plaingridT.tex} changes the following parameters and macros:
\itemitem{a)}|\baselineskip| is coerced to a dimension, i.e., any
             stretchability and shrinkability of this glue parameter
             is removed. If this changes |\baselineskip|'s value the
             user is informed via a message.
\itemitem{b)}|\vsize| becomes an integer multiple of the |\baselineskip|. If
             this changes |\vsize|'s value the user is informed via a
             message.
\itemitem{c)}|\normalbottom| is called.
\itemitem{d)}|\topskip| is set to |\baselineskip|.
\itemitem{e)}|\lineskip| is set to $\rm0\,pt$.
\itemitem{f)}|\lineskiplimit| is set to $\rm0\,pt$.
\itemitem{g)}|\parskip| is set to $\rm0\,pt$.
\itemitem{h)}|\interlinepenalty| is set to 0.
\itemitem{i)}|\clubpenalty| is set to 0.
\itemitem{j)}|\widowpenalty| is set to 0.
\itemitem{k)}|\brokenpenalty| is set to 0.
\itemitem{l)}Plain \TeX's macro |\pagebody| is changed.
\item{2.}{\tt plaingridM.tex} changes the above and the following
         parameters:
\itemitem{a)}|\abovedisplayskip| is set to $\rm0\,pt$.
\itemitem{b)}|\belowdisplayskip| is set to $\rm0\,pt$.
\itemitem{c)}|\abovedisplayshortskip| is set to $\rm0\,pt$.
\itemitem{d)}|\belowdisplayshortskip| is set to $\rm0\,pt$.
\itemitem{e)}|\predisplaypenalty| is set to 0.
\itemitem{f)}|\postdisplaypenalty| is set to 0.
\itemitem{g)}|\displaywidowpenalty| is set to 0.
\itemitem{h)}|\everydisplay| is used by the package. The original token list
             is stored in a new token register: |\grideverydisplay|.
\item{3.}{\tt plaingridI.tex} changes the above and the following parameters
         and macros:
\itemitem{a)}|\skip\topins| is set to $\rm0\,pt$.
\itemitem{b)}|\skip\footins| is set to |\baselineskip|.
\itemitem{c)}Plain's macro |\pagecontents| is changed.
\itemitem{d)}Plain's macro |\vfootnote| is changed.
\itemitem{e)}Plain's macro |\@foot| is changed.
\gridskiponeline

The package declares one output stream and twelve registers. It uses
several scratch registers.

% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\headline{\tenrm Udo Wermuth\hfil plain-grid (version \plaingridversion)}
\newcount\nmcnt \nmcnt=1
\def\nextmacro{{\bf\number\nmcnt.}\advance\nmcnt by 1\relax}
\def\nmtextindent{\gridskiponeline\expandafter\textindent\nextmacro}
% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\gridbeginsection 3. Macros and conditionals in {\tt plaingridT.tex}

The first set of macros defines vertical skips.

 \nmtextindent|\gridskiponeline| leaves a single blank line.

 \nmtextindent|\gridbackoneline| jumps back one line.

 \nmtextindent|\gridskipmax{|$n$|}| skips $n$ lines. (Braces are
 only needed for $n>9$.) If the current page has only $m$ lines left
 with $m<n$ then $m$ lines are skipped. The next page starts at its
 first line.

 \nmtextindent|\gridsnaptonextbaseline| jumps to the next
 baseline of the grid if it is not already on one. The used amount is
 always written to the log.

 \nmtextindent|\gridskiphalfaline| skips---as its name
 in\-di\-cates---$0.5 \times|\baselineskip|$. Thus, it leaves the grid
 structure. It can be used to work in a two-column format with a
 shifted grid, for example, to surround some material with some
 space. As an example, see the macro |\gridproclaim|.

 \nmtextindent|\grideject| fills the current page and ejects it.

 \nmtextindent|\gridbye| ejects the current page, performs like
 |\bye| a |\supereject|, and ends the \TeX\ run.


\gridskiponeline
The second set of macros handles endnotes.

 \nmtextindent|\griduseendnotes| must be called to initialize the
 handling of endnotes. It prepares a file in which the endnotes are
 stored. If it is called although such a file is currently opened it
 closes this file, opens a new one, and writes a message on the
 terminal that the first file has to be loaded manually.

 \nmtextindent|\gridenfilename|: The file that stores endnotes is
 named by default {\tt endnotes.tex}. If more than one file is used a
 roman numeral is added, i.e., the second file is named {\tt
 endnotesi.tex}, then it is {\tt endnotesii.tex}, and so on. The stem
 for the file names is defined in the macro |\gridenfilename|.

 \nmtextindent|\gridendnote|, \nextmacro\enspace |\gridnoteend| start
 and end the endnote in the text. The first line of the endnote must
 be placed on the same line as the |\gridendnote| (or use |%|). The
 |\gridnoteend| must be placed left-aligned in a line by itself.

 The macro |\griduseendnotes| must be called before |\gridendnote| can
 be used. Otherwise the user gets an error message.

 I assume |\gridendnote| is called after a punctuation mark. If an
 author has other ideas---or an em-dash follows---the line after
 |\gridnoteend| should start with |\unskip| as a space is inserted.

 Endnotes are numbered. The numbering starts after every
 |\griduseendnotes| with~1.

 \nmtextindent|\gridenmark| is used to add a |\mark| to endnotes. The
 user can fill its replacement text, for example, (i)~at the start of
 every chapter with the number of the chapter or (ii)~in
 |\advancepageno| with the current page number. The |\mark| is placed
 in an |\immediate||\write|.

 Later in the section with the endnotes a running head can be defined
 that uses |\firstmark| and/or |\botmark| to help a reader to find the
 place where the endnote was used.

 \nmtextindent|\gridprintendnotes| closes the current file for
 endnotes and directly inputs it again. A user must provide a section
 title.

 I think of several use cases. (i)~All endnotes in a document are
 collected and output at the end. Call |\griduseendnotes| once at the
 beginning of the document and |\gridprintendnotes| at its end.
 (ii)~The output of the endnotes should be split with subsection
 headers, for example, by chapter. Call |\griduseendnotes| at the
 start of every chapter and load the shown file names in sequence at
 the end of the document. The last file is input with
 |\gridprintendnotes|.
 (iii)~The endnotes are output at the end of every chapter of a long
 document. Call |\griduseendnotes| at the beginning of each chapter
 and |\gridprintendnotes| at every chapter's end.

\gridskiponeline
The third set of macros defines macros to enter section headers.

 \nmtextindent|\gridbeginsection| is build after plain \TeX's
 |\beginsection|. It takes an argument delimited by |\par| or an empty
 line. The argument should be at most one line and it is output in
 bold without indentation. The macro leaves two empty lines before and
 one empty line below this output.

 If the current page has less than six lines free then the page is
 filled with empty lines and the section header appears at the top of
 the next page without white space above it but with an empty line
 below.

 The argument of\/ |\gridbeginsection| is shown on the terminal. One can
 change this by setting a conditional: |\gridhidesectiontitlestrue|.

 \nmtextindent|\gridstartsection| is like the previous macro but
 uses a different amount of white space around the section header. It
 starts at a new page if less than five lines are free on the current
 page. By default the macro skips 1.5|\baselineskip| above and
 0.5|\baselineskip| below if it appears mid-page. Thus the section
 head is not printed on a grid line but in the middle of two. For the
 skips at the start of a page see the next macro.

 \nmtextindent|\gridkeepspace| configures how the previous macro
 |\gridstartsection| behaves a the start of a page.

 The value~1 skips 0.5|\baselineskip| above and below the title, the
 value~0 none above and one line below, and with~2 one gets 1.5 lines
 above and 0.5|\baselineskip| below, i.e., the same amounts as if it
 occurs mid-page. (The default is 1.) No case leaves an author with a
 shifted grid.

 One sets the value with a definition, for example,
 |\def\gridkeepspace{1 }|.

 \nmtextindent|\gridrule| has two arguments. The first is
 optional, the second must be surrounded by parentheses. It draws a
 grid-aware horizontal rule of height $\rm0.4\,pt$, depth $\rm0\,pt$,
 and width $\rm20\,pt$. Its height and width can be changed by the
 second argument. For example, |\gridrule(height 0.8pt width 40pt)|
 creates a horizontal rule twice as long and twice as thick as with
 the default setting. The depth cannot be changed.

 The first argument raises the horizontal rule. For example,
 |\gridrule 3pt(height 0.8pt width 40pt)| draws the line of the
 previous example $\rm3\,pt$ above the baseline.


\gridskiponeline
And here is the last set of macros.

 \nmtextindent|\gridlog| determines the verbosity of
 logging. Some messages appear on the terminal (value~0), others in
 the log (value~1). Additional interesting or debugging information
 can be output with values 2 and~3. To change to level $n$ use a
 definition: |\def\gridlog{ |$n$| }|. Default is level~1.

 \nmtextindent|\gridrestoreparams| restores the plain \TeX\
 values of all changed parameters. Moreover, it restores the macro
 |\pagebody|.


\gridskiponeline
Besides macros the file defines conditionals.

 \nmtextindent|\ifgridhidesectiontitles| (default setting: false)
 configures if section headers of the two macros |\gridbeginsection|
 and |\gridstartsection| are shown on the terminal. They are shown if
 the conditional is false.

 \nmtextindent|\ifgridnewpageOK| (default setting: false) determines
 if the message that is prepared in macros |\gridbeginsection| and
 |\gridstartsection| (as well as in |\gridproclaim| and |\gridbeginbox|
 of file {\tt plaingridM.tex}) is shown or suppressed for the next
 execution. The setting true suppresses the message. For the message
 see secion 7b), item number~4.

 \nmtextindent|\ifgridshowlinenos| (default setting: false) shows
 small line numbers in the vertical distance of\/ |\baselineskip| on a
 page if it is found true at the time of the shipout.



\gridbeginsection 4. Macros and registers in {\tt plaingridM.tex}

This file adds the following macros to the above set. Note the macro
|\gridrestoreparams| is extended to restore the plain \TeX\ values of
the additionally changed parameters.

 \nmtextindent|\gridskip1/| adds a way to use a vertical skip between
 lines of a paragraph. One of 1, 2, 3, or~4 should follow the slash to
 skip 1, 1/2, 1/3, or 1/4 of the |\baselineskip|. For a value larger
 than~1 it is assumed that the macro is called two, three, or four
 times in a paragraph so that its last line on the current page is
 back on the grid. It is used together with |\gridinline| (see below)
 if the inline math does not fit into the leading.

 Use |\gridsnaptonextbaseline| after a paragraph with |\gridskip| to
 fix small rounding errors. It depends on the |\baselineskip| and the
 argument if \TeX\ can compute a perfect result.

 \nmtextindent|\gridinline| has one optional argument and must
 be called in front of inline math, i.e., it should be followed by a
 |$|. %$
 It repeats the |\gridskip| except if there is an argument. It
 should be 0, 1, 2, 3, or~4 and this value is used as argument for the
 implicit |\gridskip1/|.

 Note: Every large math construction in a line with |\gridinline| must
 be prefixed. The first performs the skip, the others must get
 |\gridinline0| to avoid multiple vertical skips. In a long formula
 use |\gridinline| only for the grid-violating constructions, so
 that \TeX\ can break the formula.

 \nmtextindent|\griddisplay| has two arguments separated by a
 colon and must be followed by |$$|.

 Usually displayed equations between double-dollar signs are handled
 by the package automatically as |\everydisplay| is used. The display
 is put into a vbox in a way that the complete display fits into the
 grid. The size of this vbox is calculated to need the smallest number
 of lines. To overrule this decision the display can be prefixed by
 |\griddisplay|$\,i$|:|$j$ to force $i$ lines for the display and to
 add $j$|\jot| space at the top. But depending on the available size
 the display might start with less than this amount of white space.

 \nmtextindent|\gridproclaim| works like \TeX's |\proclaim|. It has
 two arguments separated by a period and must be followed by |\par| or
 an empty line. The first argument is set in bold with a period an a
 horizontal skip of\/ |\enspace| after it. The second argument is
 typeset as a paragraph with a slanted font. Above and below skips of
 0.5|\baselineskip| are added. That is, the material is placed on a
 shifted grid; it is also kept at the start of a page.

 \nmtextindent|\gridbeginbox| and \nextmacro\enspace|\gridendbox| build
 a pair that can be used to surround non grid-aware material. The
 output is a vbox with a height and depth that fits into the grid
 structure. Of course, a user should remember that vboxes cannot be
 broken between pages.


\gridskiponeline
Besides macros the file declares one token register.

 \nmtextindent|\grideverydisplay| replaces |\everydisplay|. That is,
 use the new token register to define what needs to be executed at the
 start of every display.



\gridbeginsection 5. Macros in {\tt plaingridI.tex}

This file adds the following macros to the above set. Again,
|\gridrestoreparams| is extended to cover all changed parameters of
plain \TeX.


\gridskiponeline
The first set of macros handles floating figures through insertions.

 \nmtextindent|\gridmidinsert| and\hskip 0pt plus
 5pt \nextmacro\enspace|\gridtopinsert|,\break \nextmacro\enspace|\gridpageinsert|
 must always be followed by \nextmacro\enspace|\gridendinsert|. They
 work like the original plain \TeX\ macros except that they put their
 insertions into a vbox with height and depth that fits into the grid
 structure.

 A |\gridmidinsert| tries to output its material at the place where it
 appears in the text. If that material does not fit anymore on the
 page it is transformed into a |\gridtopinsert| for a following page.

 A |\gridtopinsert| is placed at the top of the current page if
 possible. Otherwise it is moved to the insertions for the next
 page. The third macro, |\gridpageinsert|, is like a |\gridtopinsert|
 except that it always needs a full page for itself. The sequence of
 these two insertion types is kept by \TeX.

 \nmtextindent|\grideotspace| is a macro that stores a factor for
 |\baselineskip|; default $0.5$. That amount of space is at least left
 at the end of a topinsert. We get white space in the interval from
 |\grideotspace| times |\baselineskip| to $(1+|\grideotspace|)$ times
 |\baselineskip|. The amount is the sum of the space added to make the
 topinsert fit into the grid and |\grideotspace|.


\gridskiponeline
The second set of macros looks at footnotes.

 \nmtextindent|\gridfootnote| is followed by the footnote text
 in curly braces. As endnotes are numbered you should use symbols for
 footnotes if they are mixed. For example, take *, \dag, \ddag,
 and \S\ per page; double and triple them if there are more than
 four, i.e., use **, \dag\dag, etc.

 Such a footnote is output at the bottom of the page in the normal
 text size. The first footnote is separated from the main text through
 a horizontal rule. Footnotes must not contain grid-violating
 material; use only plain text. They can be split between pages.

 The macro requires the new |\pagecontents|.


\gridskiponeline
The last feature fixes pages that aren't completely filled; for
example, because there was only one and not two |\gridskip1/2| on the
page.

 \nmtextindent|\ifgridragged| (default: false) determines if
 a ragged bottom is accepted or not.

 The pages in this grid package have no stretch- or
 shrinkability. They must be broken at a multiple of\/
 |\baselineskip|. If for some reason a page is shorter then the ragged
 bottom feature allows a page break without generating an underfull
 vbox warning.

 The macro requires the new |\pagecontents|.



\gridbeginsection 6. Macros in {\tt plaingridB.tex}

This file adds the following experimental macros to the above set.

 \nmtextindent|\gridboxann| and \nextmacro\enspace|\gridvbox| are used
 to add a vbox with several lines to a paragraph. Macro |\gridboxann|
 must be called in the line above the one with the vbox or in vertical
 mode for the first line. (The output becomes grid-unaware if the
 announcement for the first line is made in horizontal mode.)  Macro
 |\gridvbox| gets as first argument a number; 1 signals that this vbox
 is the tallest in the current line.

 The material for the vbox are short texts that are placed
 automatically in hboxes. Thus, a typical call is
 |\gridvbox0{first text}{second text}|. Don't use fillers, for example,
 spaces or |\relax| between the hboxes.

 \nmtextindent|\gridvtop|. This macro uses the same conventions as
 |\gridvbox| but creates a vtop not a vbox. It does not need an
 announcement.



\gridbeginsection 7. Messages

The macros write several messages and the user can configure for some
if they should be output at all. Messages on the terminal cannot be
deactivated and one message is always written to the log file. The
macro |\gridlog| determines the behavior.

 \gridskiponeline \textindent{a)}Error message: ``Missing
 |\griduseendnotes|.''  The help text for this message is: ``Call the
 macro |\gridendnote| only between |\griduseendnotes| and
 |\gridprintendnotes| (and this one only once after the first).''
 {\emergencystretch=5pt \par}

 This message is shown (i) if the user enters |\gridendnote| without
 initializing the use of endnotes with |\griduseendnotes|. The
 initialization is used to prepare the file that stores the
 endnotes. As explained in section~3 this technique allows to
 implement several use cases for endnotes.

 It's also shown (ii)~if\/ |\gridprintendnotes| is called without a
 |\griduseendnotes| since its last activation. The file with endnotes
 was closed and printed. A new file must be initialized by calling
 |\griduseendnotes|.

 When the error message is shown in case~(i) then the text of the
 endnote is output in the text.

 \gridskiponeline
 \textindent{b)}There are nine terminal messages.
 
 \item{1.}GRID: |\baselineskip| is now \<d>

 The \<d> stands for a dimension in the unit {\tt pt}. This message is
 shown if the |\baselineskip| has at the beginning a glue value with
 stretch- and/or shrinkability. Grid-aware typesetting removes any
 stretch and shrink components and keeps only the natural space.

 Change the |\baselineskip| to a dimension before the macros are
 loaded and no message is shown.
 
 \item{2.}GRID: |\vsize| changed; new value \<d> (\<k> lines)

 Again, \<d> is a dimension and \<k> represents an
 integer. Here the |\vsize| was changed as it must be an exact
 multiple of\/ |\baselineskip|.

 Change the |\vsize| to an integer multiple of\/ |\baselineskip| before
 the macros are loaded and no message is shown.

 \item{3.}GRID: file with endnotes not yet output: \<t>

 |\griduseendnotes| was called twice without printing the existing
 endnotes by calling the macro |\gridprintendnotes|. The macro opens a
 new file for the next endnotes and the author is informed that the
 file \<t> needs to be manually loaded.

 \item{4.}GRID: unexpected page ejection

 This message might indicate an error. The user wants to output a
 multiline structure as it is created, for example, by
 |\gridbeginsection|, but it's too large for the current page. Thus,
 empty lines fill the current page and the structure is output on the
 next page.

 To move the begin of a section might be okay. Then the message can be
 suppressed by setting |\gridnewpageOKtrue| in front of the section
 command. The message that is output for the movement of a displayed
 equation is not affected by the conditional and should not be
 tolerated.

 \gridskiponeline
 Messages in the file {\tt plaingridI.tex}.
 
 \item{5.}GRID: page too short; fix

 There is a footnote in the last available line on the current
 page. As there is no room for the text of the footnote the last line
 is moved to the next page leaving an underfull page. A line with more
 than one footnote might generate message no.\ 7.

 In the log you find the following text: ``The page is a line too
 short because a line with a footnote must be moved.''

 \item{6.}GRID: page ends ragged; fix

 The user left the grid on the current page, for example, with
 |\gridskiphalfaline| or |\gridskip| but does not accept to end a page
 within shifted material, i.e., we have |\gridraggedfalse|.

 \item{7.}GRID: ugly page; fix

 Something went wrong and the page is underfull. It was not
 possible to identify the root cause as in the previous two messages.

 The message is accompanied in the log by this text: ``The page is not
 filled as expected. Maybe a text line with footnotes is moved to the
 next page, a skip violates the grid, or a forbidden command was used.
 Check the |\vbox| shown in TeX's warning.''

 \gridskiponeline
 Messages in the file {\tt plaingridB.tex}.

 \item{8.}GRID: vtop moved; check

 A |\gridvtop| does not fit on the current page and must be moved to
 the beginning of the next. The current page is underfull.

 \item{9.}GRID: vbox moved; check

 A |\gridvbox| does not fit on the current page and must be moved to
 the next page. The current page is underfull.

 \gridskiponeline
 \textindent{c)}There is one log message that is always output.

 \item{1.}GRID line \<l>: |\gridsnaptonextbaseline| uses \<d>

 Here \<l> is an integer and \<d> a
 dimension. |\gridsnaptonextbaseline| was used in line \<l> of
 the currently processed file. The skip used by this macro is reported
 as \<d> in the log.

 \gridskiponeline \textindent{d)}There are four messages that are
 written to the log if\/ |\gridlog|'s replacement text stores a number
 larger than~1. Two are written if\/ |\gridlog| contains 2; otherwise
 all four are output. Often they do not reflect a user's input;
 different macros, sometimes internal, write them. They help to debug
 problems.

 \item{1.}(level 2) GRID line \<l>: available lines = \<k>

 This message is in file {\tt plaingridT.tex}. A macro wants to check
 how many lines are available on the page. The value \<k> represents
 the number of unused lines.

 \item{2.}(level 2) GRID: page (\<d>) [is bad\alt is okay\alt with
 footnote\alt has a ragged bottom\alt has a shift\alt with footnote
 has a ragged bottom\alt with footnote has a shift]

 This message is in file {\tt plaingridI.tex}. The message outputs the
 internal computation of the page's fill level, the dimension \<d>,
 and the conclusion from this computation, i.e., one of the texts
 between the brackets where \alt\ means ``or''. A page that is labeled
 ``is bad'' or ``has a shift'' is an ugly page and produces one of the
 above described terminal messages. A ``has a ragged bottom''
 indicates a page that ends in shifted material but the user set
 |\gridraggedtrue|, i.e., the user accepts such pages. The text ``with
 footnote'' indicates that the computation determines that there is a
 footnote on the page; it does not indicate a problem.

 \item{3.}(level 3) GRID line \<l>: box (\<d 1>+\<d 2>) [changed by
 (\<d 3>+\<d 4>)] output as\hfil\break (\<d 5>+\<d 6>) in \<k> lines

 A vbox is automatically created; it has height and depth of \<d 1>
 and \<d 2>. The call specifies that some white space of \<d 3>
 and \<d 4> are added to height and depth, respectively. The box is
 output with dimensions \<d 5> and \<d 6> in \<k> lines to make it fit
 into the grid.

 \item{4.}(level 3) GRID line \<l>: user's height \<k> lines or \<d 1>;
 top plus \<d 2>

 The user decided to overrule the automatism in the calculation of a
 vbox with a displayed equation and this is reported in the
 log. Dimension \<d 2> states the amount of white space that the user
 added at the top of the display.

 The two level~3 messages belong to the file {\tt
 plaingridM.tex}.

\gridbye