% \iffalse meta-comment
%
% gridset.dtx
%
%% Copyright (C) 2008-2024 Markus Kohm
%%
%% This work may be distributed and/or modified under the
%% conditions of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%% The latest version of this license is in
%% http://www.latex-project.org/lppl.txt
%% and version 1.3c or later is part of all distributions of LaTeX
%% version 2005/12/01 or later.
%%
%% This work has the LPPL maintenance status "maintained".
%%
%% The author and current maintainer of this work is
%% Markus Kohm <komascript@gmx.info>.
%%
%% This work consists of the files gridset.dtx and README.md.
%%
%% Important Recommendation:
%% The LPPL requires that distributions of the Work contain all the files of
%% the Work (see ``Important Recommendations'' at lppl.txt).
%%
%
%<*dtx>
\ifx\ProvidesFile\undfined\def\ProvidesFile#1[#2]{}\fi
\ProvidesFile{gridset.dtx}
%</dtx>
%<*dtx|package|example>
%<package>\ProvidesPackage{gridset}
%<example>\ProvidesFile{gridsetexample.tex}
                 [2024-08-17 v0.4 grid - a.k.a. in-register - setting]
%</dtx|package|example>
%<*dtx>
\ifx\documentclass\undefined
  \input docstrip.tex
  \keepsilent
  \askforoverwritefalse
  \usedir{tex/latex/gridset}
  \preamble

IMPORTANT NOTE:

This is a generated file and you are not allowed to distribute it
without the source ot the work.  See below about more informations
about the files the work consists of.

\endpreamble

  \generate{%
    \file{gridset.ins}{\from{gridset.dtx}{ins}}%
    \file{gridset.sty}{\from{gridset.dtx}{package}}%
    \file{gridsetexample.tex}{\from{gridset.dtx}{example}}%
  }

  \ifToplevel{%
    \Msg{*********************************************************************}
    \Msg{*}
    \Msg{* gridset}
    \Msg{* =======}
    \Msg{*}
    \Msg{* THIS IS AN ALPHA VERSION!}
    \Msg{* DON'T USE IT ONLY TEST IT!}
    \Msg{*}
    \Msg{* To finish the installation run}
    \Msg{* \space\space latex gridset.dtx}
    \Msg{* or}
    \Msg{* \space\space pdflatex gridset.dtx}
    \Msg{* and then copy}
    \Msg{* \space\space gridset.sty to .../tex/latex/gridset/}
    \Msg{* \space\space gridset.dvi or gridset.pdf to .../doc/latex/gridset/}
    \Msg{* \space\space gridset.dtx and README to .../source/latex/gridset/}
    \Msg{* where .../ is your local TDS tree.}
    \Msg{* On some systems you'll get the local TDS tree using:}
    \Msg{* \space\space kpsewhich -var-value=TEXMFLOCAL}
    \Msg{*}
    \Msg{*********************************************************************}
  }
\else
  \let\endbatchfile\relax
\fi
\endbatchfile
\documentclass{ltxdoc}
\begin{document}
\RecordChanges
\GetFileInfo{gridset.dtx}
\DocInput{gridset.dtx}
\end{document}
%</dtx>
% \fi ^^A meta-comment
%
% \title{Semi-Manual Grid Setting Using \textsf{gridset}%
%   \footnote{This is an alpha version! Don't use it! Only test it! There's no
%     support and everything may change!}%
% }
% \author{Markus Kohm}
% \date{\filedate~\fileversion}
% \maketitle
% \begin{abstract}
%   Grid setting\,---\,also known as strict in-register setting\,---\,is
%   something, that should be done for a lot of documents but is not easy
%   using \LaTeX{}.  Package \textsf{gridset} helps to get the information
%   needed for grid setting.  It does not implement auto grid setting, but
%   there is a command \cs{vskipnextgrid}, that moves to the next grid
%   position.  This may be enough under some circumstances.  In other
%   circumstances it may fail.  So \textsf{gridset} is only one more step for
%   grid setting not a complete solution.
%
%   \paragraph*{Important Note:} This package should have been never released,
%   because it was only a very quick implementation of an idea. You should not
%   use it for any productive purpose. It has been made for testing only. I
%   would prefer to retire it from any distribution. Nevertheless I know few
%   persons using the package. So it will be still there but without any
%   support!
% \end{abstract}
% \tableofcontents
% \section{User Manual}
%
% \DescribeMacro{\gridinterval}%
% This macro contains a number without unit!  The number is the distance
% between two grid lines in unit `scale points' (sp).  You may set it so
% another value using, e.g.
% \begin{flushleft}
%  |\newlength{\|\meta{name of your length}|}|\\
%  |\setlength{\|\meta{name of your length}|}{|\meta{new length value}|}|\\
%  |\newcounter{\|\meta{name of your counter}|}|\\
%  |\setcounter{\|\meta{name of your counter}|}{\|\meta{name of your
%        length}|}|\\
%  |\edef\gridinterval{\|\meta{name of your length}|}|\\
% \end{flushleft}
%
% \DescribeMacro{\gridbase}%
% This macro contains an integer number, that represents the y-coordinate of
% the upper start of the grid.  If you want to change it, just save a position
% and \cs{edef} the \cs{gridbase} to the y-pos of that position.
%
% Most time you don't need to change \cs{gridinterval} and \cs{gridposition},
% because they are initialized to a base line grid at start of first page.
% Because of this, it doesn't matter, that changing them is not really user
% friendly.
%
% \DescribeMacro{\SavePos}%
% \DescribeMacro{\savepos}%
% \cs{SavePos}\marg{unique name} saves informations about the current position
% to the \texttt{aux}-file.  These informations are read at next \LaTeX{} run
% and may be used (see \cs{the\dots} commands below) then. The \meta{unique
% name} has to be a position name, that is unique for all saved position
% informations of the current document. Note that the command has been renamed
% from \cs{savepos} to \cs{SavePos} in release~0.2, because Lua\TeX{} since
% 0.85 uses \cs{savepos} as a new primitive. On other engines the old name
% \cs{savepos} is still available.
%
% \DescribeMacro{\vskipnextgrid}
% This command moves to the next grid position.  To achieve this, a position
% information is saved at this and used at next \LaTeX{} run.  The used name
% of the position information is \texttt{vb!\meta{number of
% skip}}. \meta{number of skip} is the number of the current
% \cs{vskipnextgrid} usage.  Counter \texttt{gridcnt} is used to number the
% usage of \cs{vskipnextgrid}.
%
% \DescribeMacro{\thegridinfo}
% \cs{thegridinfo}\marg{name} outputs
% \begin{itemize}
% \item arabic page number of the named position,
% \item grid base, that was valid saving the information of the named
%   position,
% \item grid interval, that was valid saving the information of the named
%   position,
% \item x-coordinate of the named position,
% \item y-coordinate of the named position.
% \end{itemize}
% The coordinates and intervals are numbers without units.  The unit is `scale
% points' (sp).
%
% \DescribeMacro{\theposinfo}
% \cs{theposinfo}\marg{name} outputs
% \begin{itemize}
% \item y-coordinate of the named position,
% \item grid line number (first is 0) of the next grid position,
% \item offset of the next grid position from grid base,
% \item distance to the next grid position.
% \end{itemize}
% The coordinates, offsets and distances are numbers without units.  The unit
% is `scale points' (sp).
%
% \DescribeMacro{\theypos}
% \cs{theypos}\marg{name} outputs the y-coordinate of the named position.
%
%
% \StopEventually{\PrintIndex\PrintChanges}
%
% \section{Implementation}
%
% \iffalse meta-comment
%<*package>
% \fi ^^A meta-comment
%
% \begin{macro}{gridset@luaorpdf}
% \changes{v0.2}{2017/06/05}{new internal because of Lua\TeX~0.85}
% \begin{macro}{\gridset@pageheight}
% \changes{v0.2}{2017/06/05}{new internal because of Lua\TeX~0.85}
% \begin{macro}{\gridset@pagewidth}
% \changes{v0.2}{2017/06/05}{new internal because of Lua\TeX~0.85}
% \begin{macro}{\gridset@savepos}
% \changes{v0.2}{2017/06/05}{new internal because of Lua\TeX~0.85}
% \begin{macro}{\gridset@lastxpos}
% \changes{v0.2}{2017/06/05}{new internal because of Lua\TeX~0.85}
% \begin{macro}{\gridset@lastypos}
% \changes{v0.2}{2017/06/05}{new internal because of Lua\TeX~0.85}
% We need some locals because Lua\TeX{} changed the names of several
% primitives inherited from PDF\TeX.
%    \begin{macrocode}
\newcommand*{\gridset@luaorpdf}[1]{%
  \expandafter\newcommand\csname gridset@#1\endcsname{}%
  \ifcsname pdf#1\endcsname
    \expandafter\let\csname gridset@#1\expandafter\endcsname
    \csname pdf#1\endcsname
  \else
    \ifcsname #1\endcsname
      \expandafter\let\csname gridset@#1\expandafter\endcsname
      \csname #1\endcsname
    \else
      \PackageError{gridset}{%
        neither \expandafter\string\csname #1\endcsname\space 
        nor \xpandafter\string\csname pdf#1\endcsname\space
        defined%
      }{This package needs either PDFTeX or LuaTeX or XeTeX.}%
    \fi
  \fi
}
\gridset@luaorpdf{pageheight}
\gridset@luaorpdf{pagewidth}
\gridset@luaorpdf{savepos}
\gridset@luaorpdf{lastxpos}
\gridset@luaorpdf{lastypos}
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\gridbase}
% \changes{v0.2}{2017/06/05}{prepared for Lua\TeX~0.85}
% \begin{macro}{\gridinterval}
% \changes{v0.2}{2017/06/05}{prepared for Lua\TeX~0.85}
% These contain the grid information.  \cs{gridbase} is a integer number
% representing the absolute y coordinate of the upper end of the
% grid relative to the same reference point \cs{pdfsavepos}
% uses.  \cs{gridinterval} is a integer number representing the distance of
% two grid lines.  The unit is `scaled point' (sp) both time.
%    \begin{macrocode}
\newcommand*{\gridbase}{}
\newcommand*{\gridinterval}{}
%    \end{macrocode}
%   \cs{gridbase} and \cs{gridinterval} need to be initialized at the start of
%   the first page (fixme: shouldn't this be done at the start of every
%   page?).  We use this occasion to also initialize \cs{pdfpageheight} and
%   \cs{pdfpagewidth} if this hasn't been done already.
%    \begin{macrocode}
\AtBeginDocument{%
  \ifdim\gridset@pageheight=\z@
    \gridset@pageheight=\paperheight
  \fi
  \ifdim\gridset@pagewidth=\z@
    \gridset@pagewidth=\paperwidth
  \fi
  \begingroup
    \@tempdima=\dimexpr \gridset@pageheight - \topmargin - 1in 
                      - \headheight - \headsep 
                      - \topskip \relax
    \@tempcnta=\@tempdima
    \xdef\gridbase{\the\@tempcnta}%
    \@tempcnta=\baselineskip
    \xdef\gridinterval{\the\@tempcnta}%
  \endgroup
}
%    \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\savepos}
% \changes{v0.2}{2017/06/05}{macro renamed}
% \begin{macro}{\SavePos}
% \changes{v0.2}{2017/06/05}{new name}
% \changes{v0.2}{2017/06/05}{prepared for Lua\TeX~0.85}
% Save current position on the page to the \texttt{aux}-file.  The argument
% is a unique name for the position.  The saved informations are:
% \begin{itemize}
% \item the name of the position,
% \item the arabic page number of the page with the position,
% \item the grid base, that was valid for this position,
% \item the grid interval, that was valid for this position,
% \item the x-coordinate of the absolute position,
% \item the y-coordinate of the absolute position.
% \end{itemize}
% \begin{description}
%   \item[Todo:] Currently we use our own command \cs{newpos} to store the
%   position information in the \texttt{aux}-file. But with the extended
%   reference mechanism of \LaTeX{} since 2023-11-01 this should be replaced
%   by the new properties.
% \end{description}
%    \begin{macrocode}
\newcommand*{\SavePos}[1]{%
  \begingroup
    \gridset@savepos
    \protected@write\@auxout{}{%
      \protect\newpos{#1}{\the\count\z@}{\gridbase}{\gridinterval}{%
        \noexpand\number\gridset@lastxpos
      }{%
        \noexpand\number\gridset@lastypos
      }%
    }%
  \endgroup
}
\ifx\savepos\gridset@savepos
  \PackageInfo{gridset}{LuaTeX detected.\MessageBreak
    Note, gridset command is \string\SavePos\MessageBreak
    but not \string\savepos, which is\MessageBreak
    a LuaTeX primitive
  }%
\else
  \PackageInfo{gridset}{\string\savepos\space defined as an alias of
    \string\SavePos}%
  \newcommand*{\savepos}{\SavePos}%
\fi
%    \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\newpos}
%   This is the command, that has been written to the \texttt{aux}-file.
%   Reading the \texttt{aux}-file it defines several position dependant macros
%   to store the position information.  Reading the \texttt{aux}-file while
%   \cs{begin{document}} a double definition test is done.  Reading the
%   \texttt{aux}-file while \cs{end{document}} a test is done, if the position
%   has been changed and notes the user about needed additional \LaTeX{} runs.
%   (fixme: shouldn't the test be done with the x- and the y-coordinate
%   instead of the vskip only?)
%   The defined macros are:
%   \begin{description}
%   \item[\cs{pos@\meta{position name}@page}] the arabic page number of the
%     position
%   \item[\cs{pos@\meta{position name}@base}] the valid grid base while
%     saving the position
%   \item[\cs{pos@\meta{position name}@interval}] the valid grid interval
%     while saving the position
%   \item[\cs{pos@\meta{position name}@x}] the x-coordinate of the position
%   \item[\cs{pos@\meta{position name}@y}] the y-coordinate of the postion
%   \item[\cs{pos@\meta{position name}@line}] the number of the next grid line
%     for the position (first grid line has number 0)
%   \item[\cs{pos@\meta{position name}@offset}] distance of the next grid line
%     from the grid base
%   \item[\cs{pos@\meta{position name}@vskip}] distance to the next grid line
%     for the position
%   \end{description}
%   All values are integers. The unit to all values is `scaled points'
%   (sp). See \cs{pdfsavepos} at the pdf\TeX{} user manual for more
%   information.
%    \begin{macrocode}
\newcommand*{\newpos}[6]{%
  \grid@unique@test{#1}{#2}%
  \expandafter\global\@namedef{pos@#1@page}{#2}%
  \expandafter\global\@namedef{pos@#1@base}{#3}%
  \expandafter\global\@namedef{pos@#1@interval}{#4}%
  \expandafter\global\@namedef{pos@#1@x}{#5}%
  \expandafter\global\@namedef{pos@#1@y}{#6}%
  \begingroup
    \@tempcnta=\numexpr \@nameuse{pos@#1@base} - \@nameuse{pos@#1@y}\relax
    \@tempcnta=\numexpr \@tempcnta + \@nameuse{pos@#1@interval} - 1\relax
    \divide\@tempcnta by\@nameuse{pos@#1@interval}\relax
    \expandafter\xdef\csname pos@#1@line\endcsname{\the\@tempcnta}%
    \@tempcnta=\numexpr \@tempcnta * \@nameuse{pos@#1@interval}\relax
    \expandafter\xdef\csname pos@#1@offset\endcsname{\the\@tempcnta}%
    \@tempcnta=\numexpr \@nameuse{pos@#1@y} 
                      - ( \@nameuse{pos@#1@base} - \@tempcnta )\relax
    \expandafter\let\expandafter\@tempa\csname pos@#1@vskip\endcsname%
    \expandafter\xdef\csname pos@#1@vskip\endcsname{\the\@tempcnta}%
    \expandafter\ifx\csname pos@#1@vskip\endcsname\@tempa\else
      \grid@ReRunMessage
    \fi
  \endgroup
}
%    \end{macrocode}
% \begin{macro}{\grid@unique@test}
%   A very simple test to warn if a position name isn't unique.
%    \begin{macrocode}
\newcommand*{\grid@unique@test}[2]{%
  \expandafter\ifx\csname pos@#1@page\endcsname\relax\else
    \PackageError{gridset}{position `#1' is not unique.\@gobble}{%
      You have used the position name `#1' you are using on page
      `#2'\MessageBreak
      already on page `\csname pos@#1@page\endcsname'.\MessageBreak
      You should stop processing, remove the aux-files and correct the
      names.\MessageBreak
      If you'd continue, this will result in grid position
      failures,\MessageBreak
      that won't be reported!}%
  \fi
}
%    \end{macrocode}
%   \changes{0.4}{2024/08/17}{fix deactivation of
%     \cs{grid@unique@test}
%     (\href{https://github.com/komascript/gridset/issues/1}{Issue \#1})}
%   The test should be done only, when reading the \texttt{aux} file at
%   |\begin{document}|, but not later (e.g. at |\end{document}|). So we
%   deactivate the test after reading the \texttt{aux} file in
%   |\begin{document}|.
%    \begin{macrocode}
\AtBeginDocument{%
  \global\let\grid@unique@test\@gobbletwo
}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\grid@ReRunMessage}
%   The change test will be done for each \cs{newpos} but one user information
%   at the end of the document should be enough.  So we use a message macro,
%   that destroys itself after first usage.
%    \begin{macrocode}
\newcommand*\grid@ReRunMessage{}
\AtBeginDocument{%
  \renewcommand*\grid@ReRunMessage{%
    \PackageWarningNoLine{gridset}{Grid position labels may have
      changed.\MessageBreak
      Rerun to get grid positions right}%
    \global\let\grid@ReRunMessage\relax
  }%
}
%    \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\vskipnextgrid}
% \begin{macro}{gridcnt}
% Move to next grid position.  The counter \texttt{gridcnt} is used to give
% every move to position a unique position name.  The names are
% `\texttt{vp!\meta{number of the move to position}}'.  You may use this to
% get informations e.g. about the last move to position.
%    \begin{macrocode}
\newcounter{gridcnt}
\newcommand*{\vskipnextgrid}{%
  \begingroup
    \stepcounter{gridcnt}\edef\@tempa{vp!\thegridcnt}%
    \ifvmode
%    \end{macrocode}
% \cs{pdfsavepos} in vertical mode is a problem, because the base line
% alignment will be done at least at paragraph breaking.  Because of this,
% we have to leave the vertical mode and do it then.  But remark: If you
% change the base line skip e.g. changing the font size, the next line would
% not be grid aligned!
%    \begin{macrocode}
      \leavevmode\SavePos{\@tempa}%
      \expandafter\ifx\csname pos@\@tempa @vskip\endcsname\relax
      \else
        \expandafter\ifnum \csname pos@\@tempa @vskip\endcsname =\z@\else
          \PackageInfo{gridset}{%
            vmode \string\vskip\csname pos@\@tempa @vskip\endcsname sp%
          }%
          \vskip -\parskip\vskip -\baselineskip
          \expandafter\vskip\csname pos@\@tempa @vskip\endcsname sp\relax
        \fi
      \fi
    \else
%    \end{macrocode}
% \cs{pdfsavepos} in horizontal mode is a problem too, because we have to
% enter the vertical mode to do vertical skips. Because of this, the remark
% is  the same like the vertical mode remark.
%    \begin{macrocode}
      \parskip=\z@
      \SavePos{vp!\thegridcnt}%
      \expandafter\ifx\csname pos@\@tempa @vskip\endcsname\relax
      \else
        \expandafter\ifnum \csname pos@\@tempa @vskip\endcsname =\z@\else
          \PackageInfo{gridset}{%
            hmode \string\vskip\csname pos@\@tempa @vskip\endcsname sp%
          }%
          \vskip \dimexpr -\baselineskip
                          + \csname pos@\@tempa @vskip\endcsname sp\relax
%    \end{macrocode}
% \changes{v0.3}{2020/02/12}{support for twocolumn mode}
% In twocolumn mode we have to take care that in the second column we reduce
% the horizontal movement by the width of the first column plus the column
% separation.
% Note: This may fail, because the column information may be wrong
%       outside the output routine. Maybe we should add this information to
%       \cs{SavePos} or correct the x-pos there.
%    \begin{macrocode}
          \leavevmode
          \if@twoside
            \expandafter\ifodd\csname pos@\@tempa @page\endcsname\relax
              \hskip \dimexpr -1in - \oddsidemargin - \parindent
                            \if@twocolumn\if@firstcolumn\else
                              - \columnwidth - \columnsep
                            \fi\fi
                              + \csname pos@\@tempa @x\endcsname sp\relax
            \else
              \hskip \dimexpr -1in - \evensidemargin - \parindent
                            \if@twocolumn\if@firstcolumn\else
                              - \columnwidth - \columnsep
                            \fi\fi
                              + \csname pos@\@tempa @x\endcsname sp\relax
            \fi
          \else
            \hskip \dimexpr -1in - \oddsidemargin - \parindent 
                            \if@twocolumn\if@firstcolumn\else
                              - \columnwidth - \columnsep
                            \fi\fi
                            + \csname pos@\@tempa @x\endcsname sp\relax
          \fi
        \fi
      \fi
    \fi
  \endgroup
}
%    \end{macrocode}
%   (fixme: A better solution would be to first move and then set the
%   position.  But that solution needs some more tests and maybe some more
%   ideas, because after moving the position is on grid and so the saved x-pos
%   would be on grid.)
% \end{macro}
% \end{macro}
%
% \begin{macro}{\thegridinfo}
% \begin{macro}{\theposinfo}
% \begin{macro}{\theypos}
% Some informations about the grid (valid for a position) or the position.
%    \begin{macrocode}
\newcommand*{\thegridinfo}[1]{%
  page=\@nameuse{pos@#1@page},
  base=\@nameuse{pos@#1@base},
  interval=\@nameuse{pos@#1@interval},
  x=\@nameuse{pos@#1@x},
  y=\@nameuse{pos@#1@y}%
}
\newcommand*{\theposinfo}[1]{%
  y=\@nameuse{pos@#1@y},
  gridline=\@nameuse{pos@#1@line},
  gridoffset=\@nameuse{pos@#1@offset},
  movedown=\@nameuse{pos@#1@vskip}%
}
\newcommand*{\theypos}[1]{\@nameuse{pos@#1@y}}
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \iffalse meta-comment
%<*FALSE>
\csname endinput\endcsname
%</FALSE>
%</package>
% \fi
%
% \section{Example}
%
% You may try the following example document.  You have to do several \LaTeX{}
% runs until no new rerun warning occurs.
% \iffalse meta-comment
%<*example>
% \fi
%    \begin{macrocode}
\documentclass[a4paper,12pt]{article}
\usepackage{gridset}
\usepackage{blindtext}
\raggedbottom

\pagestyle{myheadings}

\begin{document}
\markright{gridbase=\gridbase, gridinterval=\gridinterval\ without move down}%
\newcounter{Zeile}%
\makeatletter
\@whilenum \value{Zeile}<40\do {%
  \stepcounter{Zeile}%
  \theZeile. Zeile:
  \SavePos{\thepage.\theZeile}\thegridinfo{\thepage.\theZeile}\par
}%
\makeatother
\clearpage
\setcounter{Zeile}{0}
\makeatletter
\@whilenum \value{Zeile}<20\do {%
  \stepcounter{Zeile}%
  \theZeile. Zeile:
  \SavePos{\thepage.\theZeile}\theposinfo{\thepage.\theZeile}\par 
}%
\makeatother
\clearpage
\parskip=.5\baselineskip
\setcounter{Zeile}{0}
\makeatletter
\@whilenum \value{Zeile}<20\do {%
  \stepcounter{Zeile}%
  \theZeile. Zeile:
  \SavePos{\thepage.\theZeile}\theposinfo{\thepage.\theZeile}\par 
}%
\makeatother
\clearpage
\markright{gridbase=\gridbase, gridinterval=\gridinterval\ with real move down
at vmode}%
\parskip=.5\baselineskip
\setcounter{Zeile}{0}
\makeatletter
\@whilenum \value{Zeile}<25\do {%
  \stepcounter{Zeile}%
  \vskipnextgrid\theZeile. Zeile: \theposinfo{vp!\thegridcnt}\par
}%
\makeatother
\clearpage
\markright{gridbase=\gridbase, gridinterval=\gridinterval\ with real move down
at hmode}%
\parskip=.5\baselineskip
\setcounter{Zeile}{0}
\makeatletter
\@whilenum \value{Zeile}<25\do {%
  \stepcounter{Zeile}%
  \theZeile. Zeile: \vskipnextgrid\theposinfo{vp!\thegridcnt}\par
}%
\makeatother
\clearpage
\parskip=0pt
\blindtext
\begin{itemize}
\item Test
\item Test
\end{itemize}
\vskipnextgrid\theposinfo{vp!\thegridcnt}\blindtext

\end{document}
%    \end{macrocode}
% \iffalse meta-comment
%</example>
% \fi
%
% \Finale
%
\endinput
%
% end of `gridset.dtx'
%
%%% Local Variables:
%%% mode: docTeX
%%% TeX-master: t
%%% End:
