Re: [groff] modernize -T ascii rendering of opening single quote

[Jeff Conrad]

On Friday, February 8, 2019, Ingo Schwarze wrote

> > I think "historic" is pretty context dependent.  As nearly as I can
> > tell, ASA/ANSI X3.4 has called for 0x60 to encode "accent grave".
> 
> Absolutely not:
> 
>   http://worldpowersystems.com/ARCHIVE/codes/X3.4-1963/page5.JPG
> 
> In that standard, 0x60 was still unassigned, and in the next version,
> the ambiguity is already stated.

I should have said “has long called for”; it looks to me like this was
largely resolved by 1967:

    http://worldpowersystems.com/ARCHIVE/codes/#ASCII-1967

This is consistent with

    
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.96.678&rep=rep1&type=pdf

(see Figure 70, p. 28).  It’s also consistent with ANSI X3.4-1986:

    www.columbia.edu/kermit/ascii.html

> > Again, I think "traditional" depends on which tradition one has
> > followed.
> 
> That's why i qualified "traditional fonts" with "that provide",
> implying that modern (i.e.  Unicode-compatible) fonts always provide
> an "accent grave" at that code point.

Again, I think “modern” in this sense long predates Unicode.  But as the
HP fonts demonstrate, not all fonts followed (or follow) the ASA/ANSI
standard.  We mainly used HP terminals in the late 1980s; I can’t
remember how they handled 0x60, but it could well have been an opening
quote.  I probably didn’t notice because we mapped it to a neutral quote
in the nterm files; as I recall, it displayed properly (but it’s been 30
years, so don’t bet the ranch on it).

Perhaps it’s better to just say that some implementations used 0x60 for
an opening quote, while others used it for accent grave—without trying
to assign a time frame.  The ratio at any point in time would seem tough
to determine; I’m not sure what practical benefit would derive from
having a definitive answer anyway.

The relevant question would seem what the ratio is today.  I suspect
0x60 is overwhelmingly shown as accent grave. Moreover, as Ingo
mentioned, the neutral single quotes are the proper match for neutral double 
quotes. Let’s face it—a typewriter is a typewriter.

Jeff