-----BEGIN PGP SIGNED MESSAGE----- Marco Cimarosti wrote: > Theodore H. Smith wrote: > > [...] If I didn't know what a composite was, I'd guess it was the same > > thing as a combining sequence. > > > > However, the two are meant to be different, so it can't be the same. > > They are meant to have exactly the same meaning, appearance and behavior. > The difference is only inside the computer's memory, and should be invisible > to users. > > The purpose of the normalization algorithm above is to get rid of this > useless difference: > > - Normalization Form D (NFD) turns any precomposed accented letter into a > letter + accent sequence. > > - Normalization Form C (NFC) turns any letter + accent sequence into a > precomposed accented letter, if one exists. > > BTW, they always sold me that precomposed accented letters exist in Unicode > only because of backward compatibility with existing standards.
I don't get that argument. It is not difficult to round-trip convert between NFD and a non-Unicode standard that uses precomposed characters. Round-trip convertability of strings does not imply round-trip convertability of individual characters, and I don't see why the latter would be necessary. The only difficulty would have been if a pre-existing standard had supported both precomposed and decomposed encodings of the same combining mark. I don't think there are any such standards (other than Unicode as it is now), are there? (Obviously, an NFD-only Unicode would not have been an extension of ISO-8859-1. That wouldn't have been much of a loss; it would still have been an extension of US-ASCII.) > If this compatibility issue didn't exist, Unicode would be like NFD. And would have been much simpler and better for it, IMHO. - -- David Hopwood <[EMAIL PROTECTED]> Home page & PGP public key: http://www.users.zetnet.co.uk/hopwood/ RSA 2048-bit; fingerprint 71 8E A6 23 0E D3 4C E5 0F 69 8C D4 FA 66 15 01 Nothing in this message is intended to be legally binding. If I revoke a public key but refuse to specify why, it is because the private key has been seized under the Regulation of Investigatory Powers Act; see www.fipr.org/rip -----BEGIN PGP SIGNATURE----- Version: 2.6.3i Charset: noconv iQEVAwUBPSuImDkCAxeYt5gVAQGIjwf/dKRYcEVD5ZC5A12jmZtXrgUaS+FMcHmy 3EYhqN1Csr8aNP1JJZyz48VCd3WM9aV+vu3fieU/ADGu084pTQ97sG0ABXZeWagX WVWpGNZH8N6JQ7YHYoW1MBkx8S1t2Fg7J36ZN71KqeKsqrWUoLFosb3QGOJpSV09 1MygGi5UPn6vW8OVX1lAmUcs+ETYwVNd9aPqxmwkpwyO48PwgjdGEuIYcvXSDAac +g4CGPmc+mSIxrtw3yjkXIHkL8pzx1QE88BV2BB6VLiSaLvadm82Be4kGuQqcC4s Tpr1uhGvHG+hqKLxyyXzefEZyvYi182hcFXbS+7vqhEtWnPDRayAFQ== =yELZ -----END PGP SIGNATURE-----
