Character Range: surrogate blocks

Tim Bray tbray at
Sun Oct 18 03:50:25 BST 1998

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

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