% Application example, for the use of vruler.sty
\documentclass[twoside]{article}
\usepackage{vruler}
\setlength{\textwidth}{2.5in}
\setlength{\oddsidemargin}{3cm}
\setlength{\evensidemargin}{6cm}
\overfullrule=0pt \parindent=0pt
\begin{document}
\advance\textwidth 3cm %2cm is better for plain TeX
\setvruler [][][][][][\textwidth]
This is a simple example, in which we have
placed vertical rulers on the left for
odd numbered pages and on the right for
even numbered pages. \newpage
This is the second page and is thus an even
numbered page. Please see that the vertical
ruler is now on the right, and is approximately
of the same distance from the text margin as
the vertical ruler on the first page from
the left margin there. \newpage
\unsetvruler
The following pages, in fact only this page, will
not be appended with the vertical rulers.\newpage
\setvruler[][\rulercount]
This page will be added with the vertical ruler again.
Here the numbering marking of the vertical ruler picks
up where it was left. Nevertheless, we may start with
any new number. \newpage
This is another page. Please see that both this and
the previous pages have vruler on the left side.
\end{document}