[tex-eplain] Incompatibility: Eplain 3.4 and AMSTeX 2.2?

[Stefan Becuwe]

Hello,

I'm using TL 2010 with Eplain 3.4, AMSTeX 2.2, amsppt 2.2.  It seems
they don't like to work together.  Same setup with Eplain 2.8.1,
AMSTeX 2.1, amsppt 2.1h did work.

Consider following input file:

\input amstex
\documentstyle{amsppt}
\input amssym.def

\input eplain
\input miniltx
\beginpackages
\usepackage{graphicx}
\endpackages

Test

\eqdefn{eq:al}
$$\align
a &= b \tag\eqsubdef{eq:a}\\
c &= d \tag\eqsubdef{eq:b}
\endalign$$


\bye

Any idea how to solve following two errors?  Thanks in advance.

Regards


Stefan


%% first error

[...]
(/opt/texlive/2010/texmf-dist/tex/eplain/eplain.tex
! Missing \endcsname inserted.
<to be read again>
                    \futurelet 
\FN@ ->\futurelet
                   \next 
@->\FN@
         \at@ 
\x ->\endgroup \expandafter \edef \csname ifpdf@
                                                 AtEnd\endcsname {\catcode 35...
l.126 \x


%% error related to eqsubdef

! You can't use `\eqno' in restricted horizontal mode.
\eqnum ->\eqno

<argument> ...toreeqno = \@restoreeqno \fi \eqnum
                                                   \eqsubdefn {eq:a}\let \@op...