OmitXmlDeclaration of XslCompiledTransform

I use xslt document to transform xml. The xslt doc's output setting is as follows:

<xsltylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns="www.stl.com">
<xslutput method="xml" version="1.0" encoding="UTF-8" indent="yes" omit-xml-declaration="yes"/>

At runtime, XslCompiledTransform's OmitXmlDeclaration is true and the Encoding is UTF-8, however, the transformed xml output has xml declaration and the encoding is UTF-16.

< xml version="1.0" encoding="UTF-16" >

i really appreciate if someone can explain why the output xml is different from the OmitXmlDeclaration's runtime value.

Thank you for you help. Derek, you are right. I use XmlWriter with the Transform method and i didn't set XmlWriterSettings's OmitXmlDeclaration to true(defalut value is false). The following code works:

XslCompiledTransform xslt1 = new XslCompiledTransform();
xslt1.Load(reader1);

XPathDocument doc1 = new XPathDocument(new StringReader(source));

StringBuilder sb1 = new StringBuilder();

XmlWriterSettings settings = new XmlWriterSettings();
settings.OmitXmlDeclaration = true;
settings.Encoding = System.Text.Encoding.UTF8;
XmlWriter xsltOutput1 = XmlWriter.Create(sb1,settings);

But i still has a question. when the XmlWriter is being used with the Transform method, does the XslCompiledTransform's OutputSettings such as OmitXmlDeclaration & Encoding has no effect in the xml declaration and encoding of the transformed xml

If you are transforming to an XmlWriter and want the xslutput settings of the stylesheet to be used then you are supposed to pass the property OutputSettings of the XslCompiledTransform instance to XmlWriter.Create e.g.