Hi Ingo,
> 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.
--
Cheers, Ralph.
