We're producing an e-facsimile edition of a set of surveyors'
notebooks, in which individual notebooks will comprise <tei.2>
elements and entry sections will be represented as <div1>s. This
project is somewhat unusual in that the main access points will be
geographic areas rather than words in the text. For instance, a user
will want to find all notebook entries relating to "Township 3 North,
Range 5 East, Line 54" (Township and Range are PLSS data elements;
Line is a local construct). The set of surveyors' notebooks will
eventually be one component of a larger set of (non-textual) GIS
resources using the same access points.

The question, of course, is finding the most appropriate way to
encode this information within the TEI framework. The geographic
attributes will adhere to <tei.2> and <div1> elements, neither of
which seem to come with elements or attributes to encode this sort of
metadata. My question, then, is not so much whether to modify TEI but
rather how. Defining new attributes seems to be the most logical way
to go, but in many cases a single "entry" will cover multiple PLSS
values. My hunch is to do it like this:

<tei.2 plss="T003NR004E T003NR005E T003NR006E">
<div1 type="line survey" plss="T003NR005E" line="54"

Has anyone else applied item-level GIS metadata to TEI texts?