An XML document corresponds to which FRBR Group 1 entity?

The FRBR [Functional Requirements for Bibliographic Records], released by the International Federation of Library Associations and Institutions in 1998, generalizes and refines current practices and theory in library cataloging, presenting a compelling natural ontology of entities, attributes, and relationships for representing the “bibliographic universe”. The FRBR framework is extremely influential and increasingly accepted as a conceptual foundation for cataloging practice and technology in libraries and elsewhere. XML documents as defined in the W3C XML 1.0 specification, are now an important part of this bibliographic universe and it is natural to ask to which of FRBR’s “Group 1” entities does the XML document correspond. Curiously, there seem to be conflicting arguments for assigning the XML document to either of the two plausible entity categories: manifestation and expression. We believe these difficulties illuminate both the nature of the FRBR entities, and the nature of markup. We explore a conjecture that an XML document has a double aspect and that whether it is a FRBR manifestation or a FRBR expression depends upon context and intention. Such a double-aspected nature would not only be consistent with previous arguments that the meaning of XML markup varies in “illocutionary force” according to context of use, but might also help resolve an old puzzle in the humanities computing community as to whether markup is “part of” the text [buzzetti02]. However, there are alternative resolutions to explore as well and we seem to still be some distance from a full understanding of the issues. An XML document corresponds to which FRBR Group 1 entity?