U+2025 TWO DOT LEADER is also an XCCS compatibility character. It corresponds to XCCS 356B/243B (0xEEA3) "Leader, two-dot on an en body" *and* to 041B/105B (0x2145) "Leader, two-dot on an em body". The difference in width was considered a formatting distinction and was unified away in creating the U+2025 encoded character, as preserving that distinction in plain text was considered unnecessary by the Xerox representative to the committee at the time.
U+2026 HORIZONTAL ELLIPSIS maps to the ellipsis seen in a
number of legacy character encodings, including the Macintosh
character sets, but also maps to an XCCS character: 041B/104B
(0x2144) "Leader, three-dot on an em body".
Interesting.
The intent of the first two characters in the Unicode standard are rather vague.
The name TWO DOT LEADER might mean two baseline dots taking up twice the space of a one dot leader, presumably to allow a leader to be constructed with less keystrokes in the days of manual typography or fewer sorts in the days of manual typesetting.
Or TWO DOT LEADER might mean two dots which take up the same space as the one dot in the ONE DOT LEADER, to provide a denser leader (possibly with finer dots?)
The second seems close to what was intended.
Perhaps a note should be attached to these characters indicating that the ONE DOT LEADER was originally intended for leaders with one dot per en and the TWO DOT LEADER was intended for leaders with two dots per en or per em, to give some guidance to font creators and users.
Though probably of little pratical use, the presence of either U+2024 or U+2025 might be used as a hint for any application explicitly rendering from plain text to an internal fancy text format that these are leaders.
This seems to be what Philippe is suggesting, and it seems to me a reasonable thing for an application to do, but *only* if done explicitly and openly as a user-requested reinterpretation of the text.
(I would not expect or want HTML or XML or text readers to do anything with these characters except show them as they find them.)
A wordprocessing or desktop publishing application could use the forms and sizes of the dots in these characters in the current font as the basis for creating its own leaders (going instead to the full stop if these characters are empty).
Jim Allan
