Modified version of PdfSharp.XPS library for use in YellowstoneApi.
PdfSharp.XPS library copied from nathanpjones http://www.nathanpjones.com/wp/2013/03/output-to-pdf-in-wpf-for-free/
PDFsharp.XPS is published under the MIT License.
The official project web site:
http://pdfsharp.net/