On Wed, May 23, 2018 at 05:41:44PM -0000, Erik Siegel erik@xxxxxxxxxxx scripsit:
>    I have a problem that is Unicode related. Some Unicode characters (for
>    instance emojis) can have some code *following* the actual character to
>    indicate a variant. For instance in the following stylesheet, the emoji
>    character in $x (U+1F61C) is followed by U+DE1C. When I look in oXygen it
>    shows me this. But when I run the stylesheet it reports a string length of
>    1 and only a single codepoint.
> 
>    I suppose that is true, it is onlyB  single character. But how can I find
>    out (in XPath) what the value of the second bcharacterb (indicator?) is?
>    Or is that impossible anyway?

If I try to look up U+DE1C, I am informed that this is not a Unicode
code point.   It is the second half the UTF-16 surrogate pair --
D83D DE1C -- use to represent U+1F61C in UTF-16.

(See <https://apps.timwhitlock.info/unicode/inspect?s=%F0%9F%98%9C> )

I would suppose that oXygen is showing you UTF-16 source but the
processing is happening in UTF-8, where the emoji is a single code point
and corresponding glyph.

-- Graydon