[tex-eplain] German.sty does not work in (e)plain.tex

[Karl Berry]

Hi Michael,

    \addlanguage {German}{xu-dehypht.tex}{}{2}{3}

That needs to be german with a lowercase g (and rebuild the format).
Sorry, didn't notice that before.  In general, \addlanguage{foo} defines
\lang at foo, for any foo.

This is assuming your \addlanguage is the same as mine (let's hope).
Mine looks like this, from etex.src:

\def \addlanguage #1#2#3#4#5% language patterns exceptions lhm rhm
    {\expandafter \et at xlang \csname lang@#1\endcsname
     \expandafter \chardef \csname lhm@#1\endcsname=#4 % V1.0-1
     \expandafter \chardef \csname rhm@#1\endcsname=#5 % V1.0-1
     \uselanguage {#1}%
     \input #2
     \if *#3*\else \input #3 \fi
     \ifdefined \addlanguage at hook % V1.0-4
        \addlanguage at hook {#1}%  % V1.0-4
     \fi
     \edef \fmtversion {\fmtversion/#1}%
    }

Hoping,
Karl

P.S. Alternatively, I guess you could change the new line to:
\catcode`@=11\def\l at german{\lang at German}\catcode`@=12
But this does not seem clean to me.