Big questions, involving lots of technical details about encodings and font-handling. In this day and age do you really want strict adherence to Big-5, or just to limit CJK characters to the 13,000-plus included in Big-5? Unicode absorbed the Big-5 character set early on (and eventually so did GuoBiao). Since v. 2 introduced Unicode compatibility many years ago, InDesign has been able to use user-installed Unicode-compatible Big-5 fonts (available from Arphic and others) and export characters from those fonts to PDF. In fact, even the English-language versions of InDesign since 2.0 have come with Chinese fonts -- but note that even the earliest (Adobe Ming Std) offered more characters than Big-5. One neat trick: if you have installed a Big-5-only Chinese font and then apply it to all your CJK characters you will get blanks for any characters not in Big-5 (under some circumstances highlighted with "dreaded pink boxes"), a feature I often use to find non-Big-5 CJK characters. In contrast, when MS Word encounters a character missing from a font it silently swaps in a substitute from another installed font.
As for Postscript, bear in mind that its achieving CJK compatibility may have been ground-breaking when it occurred (mid-1990s?) but it is now
long in the tooth.
David, thanks for this little history of Big-5! It's one of those things I know by name only, not from any first hand experience.
So the question back to the OP would be:
InDesign can use Big-5 characters in the sense that it transparently uses them, along with all non-Big-5 Unicode characters, and (given the right font) it won't even notice the difference. Is it important that your document exclusively uses Big-5 characters? If so, it seems all you have to do is select a font that does, as David says.
A long time ago (in a galaxy far, far away) I used to think of Big-5 as very conservative, eschewing more popular variant forms in favor of the most orthodox, small-t traditional versions of Chinese characters. Eventually, I came to realize that Taiwan's five largest computer companies actually had a more serious goal in mind when they created the character set: to squeeze as many characters as they could into the limited slots available, while simultaneously avoiding variant forms that would complicate text processing.
Then along came Unicode, which for a while seemed never to meet a variant form it didn't think worthy of its own code-point: e.g., 說 [U+8AAA] versus 説 [U+8AAC], both meaning "to say" and differing only in the angle of the "ears." The upshot is that if you want to search for a phrase containing the Chinese word for "novel" (小說), your search routine must be smart enough to account for both "traditional" variants; throw in the "simplified" version (说) and you have three valid characters for one half of one "word." Happily, personal computers now have the horsepower to run such routines, but I started out in simpler times, and will always think fondly of Big-5.
Thanks Jongware and David for the advice!
Below is my understanding so far. Please correct me if I'm wrong:
Although Unicode absorbs Big5, but I believe the code point is not exact match. Since InDesign is navitely Unicode, when we do a "copy" of text from a Big5-encoded text file, and "paste" it in InDesign, Adobe must have done some magic to map the character's Big5 code points to the Unicode ones, and subsequently the document will be saved as a Unicode file. Unless the Big5 font also supports Unicode, else when the font is applied to the text, some characters will appear as boxes or may even appear incorrectly. Then there is an issue of how the InDesign page can be exported as a Big5 PDF or PS in order for the printing device to output it correctly.
So there are two constraints:
1. Printing device only supports Big5-encoded PDF or PS - no plan to change this yet.
2. Font license purchased is only for Big5 - no plan to "upgrade" it to be Unicode compatible or change to another font yet.
Further advice appreciated. Thanks in advance!
Yes the codes are different in the various encodings, and indeed ID, PDF, and the operating system all contribute "magic" to swap things around. Still, there is the expression "If it looks like a duck, quacks like a duck and walks like a duck, it is a duck." This can fail in special circumstances, and PDF's handling of Big-5 may or may not be one. Obviously, a lot depends on the software feeding the PDF to your printing device. And if your Big-5 fonts are among those that do not allow embedding in PDF then you won't even get that far. The font vendor should know, but quickest way to find out whether ID will work for you might be to install the free trial on your system and test it there.
You speak of not changing your workflow yet. I'm a print kinda guy, but I can't ignore the growth of electronic publication, where sticking strictly with Big-5 would be a serious liability. And then there are custom characters: over the years I must have created thousands that were missing from various Chinese fonts. Big-5's 13,000 seemed vast in 1990, but is now dwarfed by Unicode — in 2001, CJK Extension B added some 40,000, for a total of around 70,000 (still not enough for some specialized jobs). Are you aware that the Adobe Song Std font bundled with English-language ID not only offers 30,000 chars., but is also enhanced with Opentype's variant forms "feature" so that you can use ID's Glyphs panel to swap simplified forms for traditional? (I don't know how good the coverage is, and Adobe Song cannot turn traditional into simplified — though some of the bundled Japanese fonts can.) Hover over a Chinese character in the Glyphs panel and ID will tell you its Unicode and Big-5 or GB encoding (the Alt-X trick in Wordpad and Word speaks only Unicode). In daily work, such "magic" may not be as useful as it sounds, but it is well beyond Postscript.
As I say, I like Big-5 and it still has its uses, but I couldn't go back.