[tex-eplain] Thank you Laurence for glyph_test example; eplain won't load compatible packages

[terry.s at Safe-mail.net]

Hi Laurence and Karl,

\enablehyperlinks[dvipdfm] (by itself):
     a) turned the borders created by *eplain* around links from blue to black.
     b) allowed me to use  \hlopts{bwidth=0} to remove link borders entirely.
     c) lets me create a manual hyperlink with \hlstart ... \hlend.

Per the *eplain* manual and a 2005 article in TUGboat, *eplain* "uses" (which I took to mean "loads") "miniltx.tex" + *color*
 ... that's a (partial) misunderstanding on my part; it does load "miniltx.tex". So I tried to load *color*. To quote the article:

"The following LATEX packages (all on CTAN) are known to work under Eplain:
• autopict (LATEX picture mode);
• color (color support);
• graphics, graphicx (graphics inclusion);
• psfrag (overlay LATEX onto EPS figures);
• url (smart line breaking for URLs).

It makes sense *color* may load by default because link borders are blue by default (but it doesn't). There's color support it graphics, too (again if I understand correctly). So under the theory that the 'dvipdfm' option clashes, I removed it. With or without that option, I cannot load *color*, *graphics* or *graphicx* without error. ("miniltx.tex" is loaded by *eplain*.) *url* loaded fine all along. I have no need for *autopict* nor *psfrag* at the moment.

I visited the 3DLDF page at https://www.gnu.org/software/3dldf/glyphs.html# (and downloaded "glyph_test.tex")
I skimmed it and played with some link/color stuff (dvi-- vs. eplain). \input colordvi allows me to use \Blue as described. (So I'll be able to create a shortcut to \url to add the \Blue tag there, too.) \Blue would alternatively be defined by *color* if I could load it.

ASIDE: Thanks again, Laurence! Though your glyph test isn't very long, there are several plain-TeX techniques which are exactly some of the things I wish to learn (custom paper size, font-loading). [You said you don't use LaTeX, so FYI, \Blue is defined in the package *color*, too.]

*-*-*-*
Here is the manually-coded hyperlink (we can continue to use "btxmac-tex-test.tex"):
     \hlstart{}{bwidth=0}{https://tug.org/pracjourn/}\Blue{https://tug.org/pracjourn/}\hlend

As to the packages compatible with *eplain* here are the errors:

•   (TO BE EXPECED) With neither *color* nor "colordvi.tex" loaded:
! Undefined control sequence.
l.32 ...bwidth=0}{https://tug.org/pracjourn/}\Blue
                                                  {https://tug.org/pracjourn..

•   (NO ERROR) If I load "colordvi.tex" it works fine. \Blue works fine and clickable link text is blue.

•   If I load *color* (whether I attempt to use \Blue or not, just caused by loading):
! Undefined control sequence.
l.103 \protected
                \def\textcolor#1#{\@textcolor{#1}}

•   If I load either *graphics* or *graphicx* (my document has no graphics or drawings, this is merely caused by loading):
! Undefined control sequence.
l.120 \protected
                \def\includegraphics{%

I need sleep!
Terry S.