Venturing into versions: strategies for querying a TEI apparatus with eXist

When encoding a critical edition in XML, one of the challenges facing the text encoder is finding a way to represent multiple versions of a work in a sensible way. As usual when it comes to the electronic representation of texts in the field of the humanities, such a sensible way is provided by the Text Encoding Initiative (TEI). Actually, three ways are offered, though this post will focus on the so-called parallel-segmentation method (for extensive reference, the reader is directed to chapter 12: Critical Apparatus of the TEI Guidelines). In short: this method allows an encoder to represent all text versions of a work within a single XML source, where places with variant text are encoded as an inline apparatus (<app>), in which the distinct variants are identified as readings (<rdg wit=”[sigil]”>), whose @wit attribute links them to (an) identified version(s) of the work. At this point, a lot more could be said about both edition and markup theoretic aspects, but this won’t be the focus of this post.

Instead, this post will focus on a topic I saw myself confronted with when developing an application (i.e. a web interface) for such an edition: how do you search within such ‘multiversion’ texts? Most probably, users of the edition would want to focus on one (or a selection of) text version(s). Of course, when version 1 contains the word ‘hope’, which in version 2 had been changed to ‘despair’, (only) the right readings should be retrieved for the respective text version.