Add vertical line margin-aligned from a given point through subsequent pages

Question

Using the memoir package, I would like to have a vertical line on my margin like this:

Some leading content

      ... vertical space ...

----------------------------------
 XYZ  | Content A
      |
      | Content B
      |
      | Content C
      |
      | ...
      |
      | Content N

   *** page break ***

      | Content A1
      |
      | Content B1
      |
      | Content C2
      |
      | ...
      |

  ...

I would like the content XYZ to be in a margin note or paragraph (marginpar, and the vertical line to follow the margin of the page, with the content A being in a page the width of that area.

The content will span multiple pages, and be somewhat complex - with e.g. multiple tables that may themselves span pages, and justified content. In essence, the body of the document will be Content * - so I would like to have that be the body of the page.

So on my TODO list I have the following:

1. Set the margin of the page to be larger (\oddsidemargin);
2. Add lead-in content that is set at the standard margin position;
3. Add a vertical line along the page margin that spans multiple pages;
4. Add margin paragraphs (for "XYZ").

I had in fact figured this out before, but have since forgotten and lost how I worked it out, so am posting in part to preserve the solution but also because I'm sure just about everybody reading this will know better than I how to achieve the objective. I will post my own solution once I re-discover it.

Though I will post my answer with more details, here are my initial thoughts:

1. Using longtable or equivalent to solve 1, 2, 3 and 4 had crossed my mind, instead of mucking around with page dimensions and such, but as mentioned the "Content *" will include tables and such. It can be worked around I am sure, but it struck me as less elegant than setting the page dimensions accordingly.

2. Otherwise problems 2, 3 and 4 seem to be mostly an implementation issue with memoir, notwithstanding the vertical line - I cannot recall if that

3. If the other can be achieved, I am tempted to use the textpos package to solve problem 2.

4. Vertical rules using the e.g. 'background' package to solve problem 3.

Answer 1

What if you abused the geometry package?

%\documentclass[12pt]{memoir}
\documentclass[oneside, 12pt]{memoir}
\usepackage[showframe]{geometry}
\usepackage{lipsum,longtable}

\makeatletter % <-- all from geometry.sty, but with some lines commented out

\renewcommand*{\Gm@vrules@mpi}{%
  \hb@xt@\@tempdima{\llap%{\Gm@vrule}
  \ignorespaces
  \hskip \textwidth\Gm@vrule
  \hskip \marginparsep
  %\llap{\Gm@vrule}\hfil\Gm@vrule
}}%
\renewcommand*{\Gm@vrules@mpii}{%
  \hb@xt@\@tempdima{\hskip-\marginparwidth\hskip-\marginparsep
  %\llap{\Gm@vrule}
   \llap{}
\ignorespaces
  \hskip \marginparwidth
  \rlap{\Gm@vrule}
 \hskip \marginparsep
 \llap{}
 %  \llap{\Gm@vrule}
 \hskip\textwidth
  \rlap{}
% \rlap{\Gm@vrule}
\hss}}%
\newif\ifGm@pageframes
\Gm@pageframestrue
\renewcommand*{\Gm@pageframes}{%
  \vb@xt@\z@{%
   \ifGm@showcrop
    \vb@xt@\z@{\vskip-1\Gm@truedimen in\vskip\Gm@layoutvoffset%
     \hb@xt@\z@{\hskip-1\Gm@truedimen in\hskip\Gm@layouthoffset%
      \vb@xt@\Gm@layoutheight{%
       \let\protect\relax
       \hb@xt@\Gm@layoutwidth{\Gm@cropmark(-1,1,-3,3)\hfil\Gm@cropmark(1,1,3,3)}%
       \vfil
       \hb@xt@\Gm@layoutwidth{\Gm@cropmark(-1,-1,-3,-3)\hfil\Gm@cropmark(1,-1,3,-3)}}%
     \hss}%
    \vss}%
   \fi%
   \ifGm@showframe
    \if@twoside
     \ifodd\count\z@
       \let\@themargin\oddsidemargin
     \else
       \let\@themargin\evensidemargin
     \fi
    \fi
    \moveright\@themargin%
    \vb@xt@\z@{%
     \vskip\topmargin%\vb@xt@\z@{\vss\Gm@hrule}%
     \vskip\headheight%\vb@xt@\z@{\vss\Gm@hruled}%
     \vskip\headsep%\vb@xt@\z@{\vss\Gm@hrule}%
     \@tempdima\textwidth
     \advance\@tempdima by \marginparsep
     \advance\@tempdima by \marginparwidth
     \if@mparswitch
      \ifodd\count\z@
       \Gm@vrules@mpi
      \else
       \Gm@vrules@mpii
      \fi
     \else
      \Gm@vrules@mpi
     \fi
     % \vb@xt@\z@{\vss\Gm@hrule}%
     % \vskip\footskip\vb@xt@\z@{\vss\Gm@hruled}%
     \vss}%
    \fi%
  }}%

\makeatother

\begin{document}

a \marginpar{test}\lipsum

\newpage
b \marginpar{test}
\begin{longtable}{p{4in}}
\lipsum
\end{longtable}

\end{document}

To make for a tidier .tex file, you could wrap this in a personal package of your own, prefaced with \RequirePackage[showframe]{geometry} and then just load it on its own: \usepackage{<filename>}

Answer 2

Here is what I have done, with a preamble as follows:

\documentclass[oneside,12pt]{memoir}

\usepackage{lipsum}

\usepackage{everypage}
\usepackage[absolute]{textpos}%

% textpos settings
\setlength{\TPHorizModule}{1cm}%
\setlength{\TPVertModule}{1cm}%
\TPMargin{0.0cm}%

% page dimensions
\settrimmedsize{11in}{8.5in}{*}
\settrims{0pt}{0pt}
\settypeblocksize{8in}{10.5in}{*}
\setlrmarginsandblock{4cm}{0.5in}{*}
\setulmarginsandblock{2cm}{1.5cm}{*}
\setheaderspaces{0cm}{*}{*}
\checkandfixthelayout[nearest]

% sidebars
\sidebarmargin{left}
\renewcommand{\sidebarfont}{\footnotesize}
\setlength\sidebarwidth{2.6cm}
\setlength\sidebartopsep{6cm}
\renewcommand*{\sidebarform}{\raggedright}

To create the full-page vertical bar on every page I use everypage:

% everypage - add vertical line
\AddEverypageHook{
    % height is 29.21 (stock height - 11.5in) - 2cm - pad (2cm) = 25cm 
    \ifnum\thepage>1
    \begin{textblock}{1,25}(3.5,1)
        \rule{0.2pt}{25cm}
    \end{textblock}
    \fi
}

In the document I have on the first page:

\begin{textblock}{5}(2,2.2)
 \parbox{5cm}{%
   This appears in a static position.
 }
\end{textblock}

% horizontal line
% ~ width of stock 21.6cm (8.5in) minus 3cm for margins
\begin{textblock}{18,1}(1,7)
\rule{19.6cm}{0.2pt}
\end{textblock}

% vertical line (part of page; leaving room for header}
% ~ height is 29.21 (stock height - 11.5in) - 6cm - pad (2cm) = 21cm 
\begin{textblock}{1,21}(3.5,7)
\rule{0.2pt}{21cm}
\end{textblock}

\sidebar{Some sidebar text}

... Content A-Z

Of course, I will mark as correct an answer that substantially improves on this.