On Sunday, June 30, 2002, at 05:31 AM, James Kass wrote:
> Can you please point me to a URL for Unicode 3.2 ligature control? > This link (March 2002): > http://www.unicode.org/unicode/reports/tr28/ > ...glosses over Latin ligatures suggesting that mark-up should be > used in some cases and ZWJ in others. > The precise language of the TR is: <quote> Ligatures and Latin Typography (addition) It is the task of the rendering system to select a ligature (where ligatures are possible) as part of the task of creating the most pleasing line layout. Fonts that provide more ligatures give the rendering system more options. However, defining the locations where ligatures are possible cannot be done by the rendering system, because there are many languages in which this depends not on simple letter pair context but on the meaning of the word in question.� ZWJ and ZWNJ are to be used for the latter task, marking the non-regular cases where ligatures are required or prohibited. This is different from selecting a degree of ligation for stylistic reasons. Such selection is best done with style markup. See Unicode Technical Report #20, �Unicode in XML and other Markup Languages� for more information. </quote> That seems pretty clear to me. If you want a "ct" ligature in your document because you think it "looks cool," then you use some higher-level protocol. The "looks cool" factor simply doesn't apply unless you know what font you're dealing with, because "ct" "looks cool" in some fonts, but not others. In real Latin typography, the set of ligatures available with a typeface varies from font to font. Type designers add ligatures (or not) depending on their esthetic sense of what looks good and how the letters interact with one another. From a type design perspective, a monospaced font like Courier should have no ligatures; they don't make sense. A rich book font like Adobe Minion Pro will have a fairly large but standard set, and a calligraphic font like Linotype's Zapfino will have a huge and imaginative set. The programs that provide ligature control do so by means of having the user select a range of text and then changing the level of ligation. The type formats like OpenType or AAT support this by allowing the type designer to categorize ligatures as "common," "rare," "required," and so on. Thus, if I'm typesetting a document in Adobe InDesign, I'll select text, and turn "rare" ligatures on and thus see the "ct" ligature, if it exists in the font and if the type designer has designated it a "rare" ligature. To be frank, turning on an optional "ct" ligature throughout a document by means of inserting ZWJ everywhere you want it to take place makes as much sense in that model�the model that Western typography uses for languages such as English�as having the user insert a <i></i> pair around every letter they want in italics. Remember, Unicode is aiming at encoding *plain text*. For the bulk of Latin-based languages, ligation control is simply not a matter of *plain text*�that is, the message is still perfectly correct whether ligatures are on or off. There are some exceptional cases. The ZWJ/ZWNJ is available for such exceptional cases. ========== John H. Jenkins [EMAIL PROTECTED] [EMAIL PROTECTED] http://homepage.mac.com/jenkins/
