Re: Character Range: surrogate blocks

Tim Bray (tbray@textuality.com)
Sat, 17 Oct 1998 18:49:54 -0700


At 03:18 PM 10/17/98 -0700, Richard Emberson wrote:

>Now in production rule #2 titled Character Range
>surrogate blocks are explicitly excluded (along
>with FFFF and FFFE).

There are no Unicode characters whose numeric values
are those which appear in the surrogate blocks; the blocks
exist only to ensure the possibility of encoding non-BMP
characters unambiguously. The productions in the spec
describe the characters themselves, not any particular
encoding of them.

>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?

Yes. For example, it's legal to have 𐀁

>Short of getting a copy of the Unicode 2.0 spec, is there
>anywhere where the conversion algorithm is documented?

I strongly recommend getting a copy of the spec. It's fairly
priced and a very fine piece of work. -Tim