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\begin{document}
\title{The \Pkg{bxcjkvert} Package}
\author{Takayuki YATO (aka.~``ZR'')}
\date{v\PkgVersion\quad[\PkgDate]}
\maketitle

\begin{abstract}
This package is a tailored version of the \Pkg{CJKvert} package,
accommodated for Japanese typesetting,
where mixture of horizontal and vertical writings is common.
\end{abstract}

\tableofcontents

%===========================================================
\section{Package Loading}
\label{sec:loading}

\begin{verbatim}
\usepackage[<option>,...]{bxcjkvert}
\end{verbatim}

The \Pkg{CJKvert} package will be automatically loaded,
if not yet loaded.

The available options are described hereafter.

%-------------------
\subsection{Options for configuring font reset}

When a command for switching direction (|\CJKhorz| or |\CJKvert|)
is invoked, \Pkg{CJKvert} resets the current font parameter
by issuing |\normalfont|.
This feature is inconvenient, particularly
when authors mix different writing directions.
Thus \Pkg{bxcjkvert} suppresses the feature by default,
but it can be configured by the |resetfont| option.

\begin{itemize}
\item |resetfont=true|\Means
  Makes direction comamnds reset the current font by issuing
  the |\normalfont| command.
  \Note This is the original behavior of \Pkg{CJKvert}.
\item |resetfont=false| (default)\Means
  Makes direction comamnds retain the current font.
\end{itemize}

%-------------------
\subsection{Options for configuring adjustment of the baseline stretch}

\Pkg{CJKvert} makes some adjustment to the value of |\baselinestretch|
when the writing direction is changed.
Namely it makes the baseline stretch enlarged by the factor of
|\CJKbaselinestretch|%
\footnote{The value of \Cs{CJKbaselinestretch} is $1.3$ by default.}
when |\CJKvert| is used.

However as far as Japanese typesetting is concerned,
there is no need to tweak the baseline stretch value.
Thus \Pkg{bxcjkvert} suppresses this feature, but again
it can be configured by the |usebaselinestretch| option.


\begin{itemize}
\item |usebaselinestretch=true|\Means
  This is the same as the behavior of \Pkg{CJKvert} \emph{with}
  the |usebaselinestretch| option.
  When |\CJKvert| is invoked, the baseline stretch will be multiplied
  by the value of |\CJKbaselinestretch|.
  When |\CJKhorz| is invoked, the baseline stretch will be reverted.%
  \footnote{Note that, however, in this case the baseline stretch will
    be reverted to the value at the time when \Pkg{CJKvert} was loaded.
    it might be against authors' expectation.}
\item |usebaselinestretch=false|\Means
  This is the same as the behavior of \Pkg{CJKvert} \emph{without}
  the |usebaselinestretch| option.
  When |\CJKvert| is invoked, the baseline stretch will be set
  to the value of |\CJKbaselinestretch|.
  When |\CJKhorz| is invoked, the baseline stretch will be
  reset to $1$.
  This option ignores the user's setting to the baseline stretch.
\item |usebaselinestretch=retain| (default)\Means
  Makes direction comamnds leave the baseline stretch
  unchanged.
\end{itemize}

\Note If \Pkg{CJKvert} is loaded with the |usebaselinestretch|
option in advance,
then the value of |usebaselinestretch| of this package
will default to |true| instead of |retain|.

%-------------------
\subsection{Options for configuring initial writing direction}

\Pkg{CJKvert} sets the initial writing direction of the document
to vertical.
But \Pkg{bxcjkvert} allows authors to choose the initial direction.

\begin{itemize}
\item |main=true|\Means
  Sets the initial direction to vertical.
  \Note This is the original behavior of \Pkg{CJKvert}.
\item |main=false|\Means
  Sets the initial direction to horizontal.
\item |main=retain| (default)\Means
  Does not specify the initial direction.
  In this case, authors can use |\CJKvert| or |\CJKhorz|
  in the preamble to decide the initial direction.
\end{itemize}

%===========================================================
\end{document}