Re: [Groff] \o and \z do not work for -Tutf8

[Keith Marshall]

On 04/08/14 17:06, Bernd Warken wrote:
> For `gpinyin', the European-like Chinese, I need to create character
> overstrikes for the 1st (a macron) and the 3rd tone (a caron).
> To append an accent over the ü and Ü characters (u/U umlaut) for all
> 4 tones seems to be even more complex.
> 
> The overstrike with `\o' and `\z' preduce on `-Tpdf', etc., a plus
> sign within the digit 0 for both escapes.  But both escapes do not
> work on `-Tutf8' or `nroff': 
> 
> $ echo "A\o'0+'\z0+Z" | nroff
> A++Z
> 
> which is wrong.

It may not be what you would like, but if your output device is a video
terminal, (or emulated video terminal), it is not wrong; it is the best
you can hope to achieve, given the limitations imposed by the physical
characteristics of such devices.

> Both escapes are documented in Osanna/Kernioghan `CSTR 54' and
> many other ancient `roff' documentations.  So `nroff' should be able
> to do that as well.  Every typewriter could do such overstriking.

But a video terminal is not a typewriter.  Video terminals can display
only one glyph in each physical character cell; when you compose a
character by overstriking multiple glyphs, you will see only the last
one struck in each cell.  You can achieve no better than this.

OTOH, when a typewriter overstrikes, the accumulation of all glyphs
struck remains indelibly impressed on the printed page.

> I had also trouble with `\h' and `\v', but for that later on.

Again, you will be hamstrung by the physical limitations of the video
display device -- motions will be restricted to integer multiples of the
physical character cell size.

-- 
Regards,
Keith.