[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Character Range: surrogate blocks
Richard Emberson scripsit: > To extend the available characters in Unicode one > can use to 16 bit characters with surrogate blocks. Well, no. One uses the 16-bit *codes* in the surrogate blocks. They aren't *characters* (what in Unicode is called *abstract characters*) at all. > Now in production rule #2 titled Character Range > surrogate blocks are explicitly excluded (along > with FFFF and FFFE). Correct, because these codes do not represent characters. > Does that mean that if one were reading a character > stream that included characters not in the basic > set of Unicode characters (those not using surrogate > blocks) that it would be a wellformedness violation? I don't understand this question. Is there an extra "not" somewhere? > There are the extra, beyond 16-bit, characters specified > by the spec in production rule #2 as "[x10000-#x10FFFF]". > Is this how Unicode characters that use the surrogate > blocks get represented in an XML document? In UTF-16 (= Unicode) representation, yes. In UTF-8 representation they are represented as the appropriate 4-byte sequences. > Is there > an algorithm for the convertions defined somewhere? Same as Unicode or ISO 10646 UTF-16, namely: a codepoint in the range D800-DBFF followed by one in the range DC00-DFFF represents the character whose code is (first-D800)*400+(second-DC00)+10000 (hex arithmetic). > Short of getting a copy of the Unicode 2.0 spec, is there > anywhere where the conversion algorithm is documented? http://www.cm.spyglass.com/unicode/standard/wg2n1035.html#x10 > Why was it decided to exclude the uses of surrogate > block-base Unicode characters within XML documents? What is excluded is surrogate characters appearing in unpaired form. These could be generated, e.g. by UTF-8 ED A0 80 = U+D800. -- John Cowan cowan@c... e'osai ko sarji la lojban. xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ To (un)subscribe, mailto:majordomo@i... the following message; (un)subscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...)
|
PURCHASE STYLUS STUDIO ONLINE TODAY!Purchasing Stylus Studio from our online shop is Easy, Secure and Value Priced! Download The World's Best XML IDE!Accelerate XML development with our award-winning XML IDE - Download a free trial today! Subscribe in XML format
|