[tex-eplain] Error message with 3.0

[John R. Culleton]

I downloaded 3.0 xeplain.tex and immediately got an error
message;
---------------------------------------
! Undefined control sequence.
<recently read> \innerdef

<to be read again>
                   \innernewbox
\innerinnerdef ...erdef \csname inner#1\endcsname
                                                  {#1}
l.380 \innerinnerdef{newbox}
                            %
?                                     
---------------------------
Can anyone suggest why?

-- 
John Culleton