As a note, Zorba *does* throw XQST0090 when � appears in a single literal:
% bin/zorba -q '"�"'
<.>:1,2: static error [err:XQST0090]: "Invalid XML v1.0 codepoint in the string literal ""�""": invalid character reference in XML ; raised at /home/ceej/zo/src/src/compiler/api/compiler_api.cpp:201
As a note, Zorba *does* throw XQST0090 when � appears in a single literal:
% bin/zorba -q '"�"' zo/src/ src/compiler/ api/compiler_ api.cpp: 201
<.>:1,2: static error [err:XQST0090]: "Invalid XML v1.0 codepoint in the string literal ""�""": invalid character reference in XML ; raised at /home/ceej/