[tex-eplain] btxmac.tex causes Runaway definition and Forbidden control sequence on compile.

[Karl Berry]

Hi Terry,

    \input eplain
    \input btxmac.tex

eplain.tex already includes btxmac.tex. There is no need to include it
separately. I didn't know this \input order caused an error. I can
probably fix that, but in practice: just \input eplain and never mind
btxmac.

After you remove the \input btxmac, you'll discover you get a second,
similar-looking error about \beginsection:

Runaway argument?
Minimal Example (with eplain, btxmac.tex and url) Hello there! 
! Forbidden control sequence found while scanning use of \beginsection.

This error is because the argument to \beginsection is delimited by
\par, e.g., a blank line. Thus you need to change your input, as in:

\beginsection Minimal Example (with eplain, btxmac.tex and url)

Hello there!

Hope this helps. Thanks for posting a runnable example :). -k