XCES: An XML-based Encoding Standard for Linguistic Corpora

The Corpus Encoding Standard (CES) is a part of the EAGLES Guidelines developed by the Expert Advisory Group on Language Engineering Standards (EAGLES) that provides a set of encoding standards for corpus-based work in natural language processing applications. We have instantiated the CES as an XML application called XCES, based on the same data architecture comprised of a primary encoded text and "standoff" annotation in separate documents. Conversion to XML enables use of some of the more powerful mechanisms provided in the XML framework, including the XSLT Transformation Language, XML Schemas, and support for interrescue reference together with an extensive path syntax for pointers. In this paper, we describe the differences between the CES and XCES DTDs and demonstrate how XML mechanisms can be used to select from and manipulate annotated corpora encoded according to XCES specifications. We also provide a general overview of XML and the XML mechanisms that are most relevant to language engineering research and applications.