+
+%<*en>
+\subsection{Alternative Commands to \cs{ltjsetparameter}}
+The basic method to set parameters of \LuaTeX-ja is to use
+\cs{ltjsetparameter}~or~\cs{ltjglobalsetparameter}.
+However, these commands are slow, because they parse a key-value list,
+so several alternative commands are used in \LuaTeX-ja.
+\emph{This subsection is not for general \LuaTeX-ja users.}
+
+\paragraph{Setting \Param{kanjiskip}~or~\Param{xkanjiskip}}
+In \Pkg{ltjsclasses}, every size-changing command such as \cs{Large}
+changes \cs{kanjiskip}~and~\cs{xkanjiskip}.
+But a simple implementation, as the code below, is slow since
+two key-value lists are parsed by \cs{ltjsetparameter}:
+\begin{lstlisting}
+ \ltjsetparameter{kanjiskip=0\zw plus .1\zw minus .01\zw}
+ \@tempskipa=\ltjgetparameter{xkanjiskip}
+ \ifdim\@tempskipa>\z@
+ \if@slide
+ \ltjsetparameter{xkanjiskip=0.1em}
+ \else
+ \ltjsetparameter{xkanjiskip=0.25em plus 0.15em minus 0.06em}
+ \fi
+ \fi
+\end{lstlisting}
+
+Hence, \LuaTeX-ja defines more primitive commands, namely \cs{ltj@setpar@global},
+\cs{ltjsetkanjiskip}, and~\cs{ltjsetxkanjiskip}. Here
+\begin{quote}
+ \lstinline+\ltj@setpar@global\ltjsetkanjiskip 10pt+
+\end{quote}
+and \lstinline+\ltjsetparameter{kanjiskip=10pt}+ has the same effect.
+The actual code of \Pkg{ltjsclasses} is shown below:
+\begin{lstlisting}
+ \ltj@setpar@global
+ \ltjsetkanjiskip{\z@ plus .1\zw minus .01\zw}
+ \@tempskipa=\ltjgetparameter{xkanjiskip}
+ \ifdim\@tempskipa>\z@
+ \if@slide
+ \ltjsetxkanjiskip.1em
+ \else
+ \ltjsetxkanjiskip.25em plus .15em minus .06em
+ \fi
+ \fi
+\end{lstlisting}
+
+Note that using \cs{ltjsetkanjiskip}~or~\cs{ltjsetxkanjiskip} alone,
+that is, without executing \cs{ltj@setpar@global} in advance, is \emph{not} supported.
+%</en>
+