+あいうえおabc$-\vcenter{\noindent abc}$あいう$adxvsv\footnote{あいうえおabc}Ha$.
+
+\newpage
+
+\newpage
+\ExplSyntaxOn
+\cs_new:Nn \my_test_dir: {\texttt{
+ \platex_if_direction_yoko:T { Y }
+ \platex_if_direction_tate_nomath:T { T }
+ \platex_if_direction_dtou:T { D }
+ \platex_if_direction_utod:T { U }
+ \space
+ \platex_if_direction_tate:T { Tx }
+ \platex_if_direction_tate_math:T { Tm }
+}}
+\cs_new:Nn \my_test_box: {\texttt{
+ \platex_if_box_yoko:NT \l_tmpa_box { Y }
+ \platex_if_box_tate_nomath:NT \l_tmpa_box { T }
+ \platex_if_box_dtou:NT \l_tmpa_box { D }
+ \platex_if_box_utod:NT \l_tmpa_box { U }
+ \space
+ \platex_if_box_tate:NT \l_tmpa_box { Tx }
+ \platex_if_box_tate_math:NT \l_tmpa_box { Tm }
+}}
+
+\mode_leave_vertical:
+\hbox:n { \platex_direction_yoko: ABCあーいう \my_test_dir: }
+\hbox:n { \platex_direction_tate: ABCあーいう \my_test_dir: }
+\hbox:n { \platex_direction_dtou: ABCあーいう \my_test_dir: }
+
+\par
+\mode_leave_vertical:
+\hbox:n { \platex_direction_tate: $\hbox{PBCあーいう \my_test_dir:}$ }
+\hbox:n { \platex_direction_utod: ABCあーいう \my_test_dir: }
+
+\par
+1.~\hbox_set:Nn \l_tmpa_box { \platex_direction_yoko: ABCあーいう } \my_test_box:\par
+2.~\hbox_set:Nn \l_tmpa_box { \platex_direction_tate: ABCあーいう } \my_test_box:\par
+3.~\hbox_set:Nn \l_tmpa_box { \platex_direction_dtou: ABCあーいう } \my_test_box:\par
+4.~\hbox_set:Nn \l_tmpa_box { \platex_direction_utod: ABCあーいう } \my_test_box:\par
+5.~\hbox:n { \platex_direction_tate: $ \hbox_gset:Nn \l_tmpa_box { ABCあーいう } $ } \my_test_box:
+\ExplSyntaxOff
+
+
+\newpage
+\dtou
+あいうえお\footnote{あいうえおabc}あ
+
+\end{document}