By default when using Oracle File Adapter to produce XML documents, no encoding="<charset>" attribute is used in the <?xml version="1.0"?> processing instruction.
Default PI:
<?xml version="1.0" ?>
and wanted PI:
<?xml version="1.0" encoding="UTF-8" ?>
The way to make this work (at least in 10.1.3.4) is to update the XML schema to include two new options in the schema definition.
xmlns:nxsd="http://xmlns.oracle.com/pcbpel/nxsd"
nxsd:encoding="UTF-8">
So, adding these attributes will make the schema look like:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.fi.oracle.com/harri.kaukovuo"
elementFormDefault="qualified" attributeFormDefault="unqualified"
xmlns:nxsd="http://xmlns.oracle.com/pcbpel/nxsd"
nxsd:encoding="UTF-8">
<xs:element name="ORDERS">
...
</xs:element>
</xs:schema>