My USD 0.02, as someone who is neither a professional typographer nor a font designer (more than one, but not quite two, different things)...
Discussions about the character-glyph model often mention the "essential characteristics" of a given character. For example, a Latin capital A can be bold, italic, script, sans-serif, etc., but it must always have that essential "A-ness" such that readers of (e.g.) English can identify it as an A instead of, say, an O or a 4 or a picture of a duck. (Mark Davis has a chart showing dozens of different A's in his "Unicode Myths" presentation.) Somewhere in between the obvious relationships (A = A, B ≠ A), we have the case pair A and a. They are not identical, but they are certainly more similar to each other than are A and B. It seems to me, as a non-font guy, that calling a font a "Unicode font" implies two things: 1. It must be based on Unicode code points. For True- and OpenType fonts, this implies a Unicode cmap; for other font technologies it implies some more-or-less equivalent mechanism. The point is that glyphs must be associated with Unicode code points (not necessarily 1-to-1, of course), not merely with an internal 8-bit table that can be mapped to Unicode only through some other piece of software. 2. The glyphs must reflect the "essential characteristics" of the Unicode character to which they are mapped. That means a capital A can be bold, italic, script, sans-serif, etc. A small a can also be small-caps (or even full-size caps), but I think this is the only controversial point. In a Unicode font, U+0041 cannot be mapped to a capital A with macron, as it is in Bookshelf Symbol 1; nor to a six-pointed star, as in Monotype Sorts; nor to a hand holding up two fingers, as in Wingdings. (But it can be mapped to a "notdef" glyph, if the font makes no claim to supporting U+0041.) U+0915 absolutely can have snow on it, or be bold or italic or whatever (or all of these), as long as a Devanagari reader would recognize its essential "ka-ness." It cannot look like a Latin A, nor for that matter can U+0041 look like a Devanagari ka. Font guys, do you agree with this? Of course, the term "Unicode font" is also often used to mean "a font that covers all, or nearly all, of Unicode." Font technologies generally don't even allow this, of course, and even by the standards of "nearly" we are still limiting ourselves to things like Bitstream Cyberbit, Arial Unicode MS, Code2000, Cardo, etc. Right or wrong, this is a commonly accepted meaning for "Unicode font." -Doug Ewell Fullerton, California
