1. LREC 2000 Athens, Greece An XML-based Encoding Standard for Language Corpora Nancy Ide Vassar College Patrice Bonhomme LORIA/CNRS Laurent Romary LORIA/CNRS XCES

2. LREC 2000 Athens, Greece XCES The Corpus Encoding Standard EAGLES standard encoding conventions for corpora used in language engineering research an SGML application TEI conformant

3. LREC 2000 Athens, Greece XCES The CES defines... requirements for increasing levels of encoding a suite of DTDs for encoding basic document structure and linguistic annotation a corresponding data architecture for linguistic corpora

4. LREC 2000 Athens, Greece XCES instantiation of the CES DTDs in XML same tags, data architecture as the CES motivation: use in creating the American National Corpus (ANC) –Macleod, Ide, and Grishman, LREC 2000

5. LREC 2000 Athens, Greece XCES XML provides more than SGML better linkage mechanisms XSLT for document access and transformation XML schemas provision for accessing all or part of multiple DTDs

6. LREC 2000 Athens, Greece XCES Minimal XML conversion  adaptation of DTDs  eliminate inclusion exceptions  make mixed-content models XML-compliant adaptation of the CES mechanism for inter-document reference –meet the specifications of XML pointer and linking mechanisms

7. LREC 2000 Athens, Greece XCES Additional Adaptations validate the CES data architecture by ensuring conformance to other XML specifications –XSL Transformation Language –XQL exploit XML mechanisms for combining all or part of documents described by different DTDs instantiate the XCES DTDs using XML schemas

8. LREC 2000 Athens, Greece XCES The CES/XCES Data Architecture remote markup, or "stand-off" model annotations maintained in separate documents that point back to the original yields a “hyper-document” composed of the original text and all annotations increasingly accepted as the appropriate architecture for language resources

9. LREC 2000 Athens, Greece XCES Use of links in CES and XCES link corresponding segments of two or more aligned primary texts link annotation documents to a base document containing the primary text –e.g., morpho-syntactic information linked to the string of characters in the original text to which it applies

10. LREC 2000 Athens, Greece XCES XCES Requirements for Linking must be able to point to other documents must be able to point to tagged elements as well as locations within tagged elements –eliminate the need to tag every element that might be referenced –eliminate IDs on every element that is referenced, as in SGML

11. LREC 2000 Athens, Greece XCES XML Path Language (XPath) concise notation for element localization in the document tree –/div/p[2]/s[3] - third sentence of second paragraph in each –/descendant::p - all elements predicates for accessing characters within elements –substring(/p/s[2]/text(),10,12)

12. LREC 2000 Athens, Greece XCES XPointer extends XPath syntax to allow : –addressing points and ranges as well as nodes –locating information by string matching –use of addressing expressions in URI- references as fragment identifiers

13. LREC 2000 Athens, Greece XCES XLink uni- or multi-directional links can specify how link is to be activated –by hand or automatically by the browser can specify what to do with the target fragment –replace it or insert it into the source document

14. LREC 2000 Athens, Greece XCES Links to External Documents None in SGML HyTime/TEI invented "doc" attribute CES used "doc" with inheritance to avoid repetition of the attribute –not supported by SGML processors XML: XLink and xml:base attribute

15. LREC 2000 Athens, Greece XCES Linking Mechanisms (A brief history) <tok from="CHILD (1) (2) STRLOC (10)" to="CHILD (1) (2) STRLOC (22)" doc="doc.xml"> <tok xlink:href= "http://www.loria.fr/doc.xml#xptr (substring(/p/s[2]/text(),10,12))"> CES XCES using XLink HyTime/TEI

16. LREC 2000 Athens, Greece XCES Use of xml:base <chunk xml:base= "http://www.loria.fr/doc.xml#"> <tok xlink:href="xptr(substring (/p/s[2]/text(), 10, 12))"/> <tok xlink:href="xptr(substring (/p/s[2]/text(), 24, 4))"/>

17. LREC 2000 Athens, Greece XCES XSLT a powerful tree-traversal language translate any XML document into another document in any form –html –XML –plain text –etc. most to offer for handling annotated corpora

18. LREC 2000 Athens, Greece XCES XSLT Capabilities  selection of elements or portions of element content using the XPath syntax  rearrangement, transformation of extracted information (text content, element names, etc.) in the target document addition of information to the target document

19. LREC 2000 Athens, Greece XCES A Simple Example <chunk type="BODY" lang="en" xml:base= "http://www.cs.vassar.edu/~ME/Oen.xcesDoc#"> <tok type="WORD" xlink:href= "xptr(substring(//p/s[1]/text(),1,2"> It it Pp3ns PPER3 it Pp3ns PPER3... xcesAna document xcesAna document

20. LREC 2000 Athens, Greece XCES <xsl:stylesheet version="1.0" xmnls:xsl= "http://www.w3.org/1999/XSL/Transform"> | | XSLT creates HTML XSLT document XSLT document

21. LREC 2000 Athens, Greece XCES Result It|it|PPER3 was|be|PAST3 a|a|DINT bright|bright|ADJE cold|cold|ADJE day|day|NN…

22. LREC 2000 Athens, Greece XCES Possibilities create new documents containing selected annotations transduce XML encoded documents to tool- internal formats generate a new document with all phonemes that appear in a certain context (or all the unique contexts of a certain phoneme), etc.

23. LREC 2000 Athens, Greece XCES XML Schemas constrain and document the meaning, usage and relationships of the constituent parts of XML documents –datatypes –elements and their content –attributes and their values provide default values for attributes and elements

24. LREC 2000 Athens, Greece XCES Impact for language resources provide means to define an abstract data model for a class of documents –e.g., data model for annotations and annotated objects –one of the most important tasks for corpus and tool creators provide for much tighter validation of document form and content

25. LREC 2000 Athens, Greece XCES Capabilities different attribute declarations and/or content models can apply to elements with the same name in different contexts –allows for more tightly constrained content models than possible with DTDs –e.g., in header and in text likely have different content constraints

26. LREC 2000 Athens, Greece XCES define equivalence classes for groups of elements and/or attributes –may be used in the same ways as defined for a particular named element in CES used parameter entities to make a class of phrase-level objects (for example) – a "kludge"

27. LREC 2000 Athens, Greece XCES constrain attribute or element values (or combinations) to be unique, e.g., –only one entry in a computational lexicon can be defined with a given word form –only one paragraph can have an attribute indicating that it is the 23rd –only one disambiguated form is given for each token –only one correspondence for a given item in an alignment document Useful for error detection and prevention

28. LREC 2000 Athens, Greece XCES establish dependencies based on element or attribute values, for example: –prevent nouns from being assigned a tense –specify that tokens with type attribute value PUNCT include only elements containing specific characters –specify annotation labels elsewhere, constrain element content to these values only e.g., constrain the values of the element in an XCES annotation document to the EAGLES morpho-syntactic specifications Another means for error control and validation

29. LREC 2000 Athens, Greece XCES Why is XML a good thing? search, extraction, and transformation capabilities answer most current and foreseen needs for corpus-based language engineering means to fully implement the CES/XCES data architecture processing tools for XML recommendations are freely distributed –no need for costly and time-consuming tool development

30. LREC 2000 Athens, Greece XCES XCES and its future CES and XCES have been developed for and by the language engineering community At present, cover –various features in written text –morpho-syntactic annotation –alignment information relatively stable and agreed-upon within the community

31. LREC 2000 Athens, Greece XCES coverage will continue to evolve currently working with different groups to implement encoding guidelines for –additional written text features –computational lexicons –discourse and dialogue –co-reference –speech and its various levels of annotation and representation –Asian character support

32. LREC 2000 Athens, Greece XCES Information http://www.cs.vassar.edu/CES and http://www.cs.vassar.edu/XCES http://www.cs.vassar.edu/CES and http://www.cs.vassar.edu/XCES ide@cs.vassar.edu or ide@loria.fr bonhomme@loria.fr romary@loria.fr