Question about Unicode Greek

[Robert Goulding]

I've been away from groff for a long time; I think the last time I used it,
there was no Unicode support at all. Now I'm interested in using it as a
filter from markdown, through pandoc to groff to pdf.

This is working well for me, except for a handful of files in which I use
Greek with accents. I understand that groff doesn't have characters for
accented Greek characters, and I'm willing to do the work to add them, I'm
just trying to understand what's involved.

So, here is a tiny document with some Greek in it:

.LP
ἐν ἀρχῇ ἦν ὁ λόγος, καὶ ὁ λόγος ἦν πρὸς τὸν θεόν, καὶ θεὸς ἦν ὁ λόγος

When I run this through preconv, I get the following:

.lf 1 rubbish.ms
.LP
\[u1F10]\[u03BD] \[u1F00]\[u03C1]\[u03C7]\[u1FC7] \[u1F26]\[u03BD] \[u1F41]
\[u03BB]\[u03CC]\[u03B3]\[u03BF]\[u03C2], \[u03BA]\[u03B1]\[u1F76] \[u1F41]
\[u03BB]\[u03CC]\[u03B3]\[u03BF]\[u03C2] \[u1F26]\[u03BD]
\[u03C0]\[u03C1]\[u1F78]\[u03C2] \[u03C4]\[u1F78]\[u03BD]
\[u03B8]\[u03B5]\[u03CC]\[u03BD], \[u03BA]\[u03B1]\[u1F76]
\[u03B8]\[u03B5]\[u1F78]\[u03C2u] \[u1F26]\[u03BD] \[u1F41]
\[u03BB]\[u03CC]\[u03B3]\[u03BF]\[u03C2].

with all of the Unicode characters turned into the correct code numbers.
When I run this through groff -ms -Tps I get the following errors:

troff: rubbish.ms:2: warning: can't find special character 'u03B5_0313'
troff: rubbish.ms:2: warning: can't find special character 'u03B1_0313'
troff: rubbish.ms:2: warning: can't find special character 'u03B7_0342_0345'
troff: rubbish.ms:2: warning: can't find special character 'u03B7_0313_0342'
troff: rubbish.ms:2: warning: can't find special character 'u03BF_0314'
troff: rubbish.ms:2: warning: can't find special character 'u03BF_0301'
troff: rubbish.ms:2: warning: can't find special character 'u03B9_0300'
troff: rubbish.ms:2: warning: can't find special character 'u03BF_0300'

This is what is puzzling me. The very first letter, ἐ, is correctly given
its unicode description \[u1F10] by preconv; but then troff seems to
decompose it into \[u03B5] which is ε and \[u0313] which is ̓ . So, if I
wanted to tell groff how to print ἐ, how do I go about it, when there seem
to be two internal representations?

Thanks very much - Robert.

-- 
Robert Goulding
Director, John J. Reilly Center for Science, Technology, and Values;
Director, Program in History and Philosophy of Science;
Assoc. Professor, Program of Liberal Studies,
Fellow, Medieval Institute,
University of Notre Dame.