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

[Ingo Schwarze]

Hi Ralph,

i do not disagree with anything you are saying in the following
mail, and did not intend to say anything contradicting the points
you clarify, i merely aimed for being shorter and tried to refrain
from talking about closing quotes at all because there is no
contention with respect to them, and i refrained from discussing
how the accents are supposed to be used because the patch has no
affect on the input or output of accents.

Yours,
  Ingo


Ralph Corderoy wrote on Mon, Feb 18, 2019 at 12:22:34PM +0000:

>> The latest US-ASCII standard, ANSI INCITS 4-1986 (R2007),
>>
>>   http://sliderule.mraiow.com/w/images/7/73/ASCII.pdf
>>
>> says on page 16;
>>
>>   0x60 LEFT SINGLE QUOTATION MARK, GRAVE ACCENT
>>
>> with this footnote:
>>
>>   These characters should not be used in international interchange
>>   without determining that there is agreement between sender and
>>   recipient (see Section B5 in Appendix B).
>>
>> which appears to go back to at least RFC 20 (yes, *twenty*), 1969:
>>
>>   http://art.tools.ietf.org/html/rfc20  (page 5)

> I think you have misinterpreted the above.
> The table on physical page 16 of the above US-ASCII standard says
> 
>     Graphic  Name                       Coded Representation
>        '     Apostrophe, Right Single
>                Quotation Mark,
>                Acute Accent*            2/7
>        `     Left Single
>                Quotation Mark,
>                Grave Accent†            6/0
> 
>     *The use of the symbols in 2/2, 2/7, 2/12, 5/14, and 7/14
>      as diacritical marks is described in A5.2 in Appendix A.
>     †These characters should not be used in international interchange
>      without determining that there is agreement between sender and
>      recipient (see Section B5 in Appendix B).
> 
> That makes clear that 27 and 60 are paired as left and right single
> quotation marks.
> 
> The referenced A5.2 is
> 
>     A5.2  In order to permit the representation of languages other than
>     English, two diacritical (or accent) marks have been included, and
>     provision has been made for the use of four punctuation symbols
>     alternatively as diacritical marks in conjunction with backspace.
>     (The use of BS to form composite characters is now deprecated (see
>     Section 5)).  The pairing of these punctuation symbols with their
>     corresponding diacritical marks was done to facilitate the design of
>     a typeface that would be acceptable for both uses.  These
>     arrangements are given in Table A1. 
> 
>                         Table A1 
>               Punctuation and Diacritical Marks 
> 
>       Col/  Code Table  ____________ Use _____________
>       Row     Symbol      Punctuation     Diacritical
> 
>       2/2       "       QUOTATION MARK    DIAERESIS
>       2/7       '       APOSTROPHE        ACUTE ACCENT
>       2/12      ,       COMMA             CEDILLA
>       5/14      ^       (None)            CIRCUMFLEX
>       6/0       `       LEFT SINGLE
>                             QUOTATION MARK  GRAVE ACCENT
>       7/14      ~       (None~            TILDE
> 
> This re-states 60 is a left single quotation mark.  It also makes clear
> that 27's diacritical use is as an acute accent.  A5.2 says the aim is
> `a typeface that would be acceptable for both uses'.  Thus one that
> makes 60 and 27 look like a left/right pair of single quotes, and also
> grave and acute accents for over-striking.
> 
> RFC 20, that you cite, makes the same case but calls them opening and
> closing single quotation mark instead of left and right.
 
>> While that of course cannot retroactively change what ASCII used to
>> define in the 1960ies to 1980ies, i do think an argument can be made
>> that there is value in discontinuing usage of ASCII that conflicts
>> with Unicode before we enter the third decade of the new millenium.

> ASCII is ASCII.  Unicode may choose to change the interpretation of its
> runes that overlap, but it doesn't change ASCII.