Thanks to all that have responded  to my query on how to check TARGETS values.
In the end I followed Sebastian's advice and wrote a Xquery to check them,
though Schematron is probably the way to go in the future (I just don't have the time this weekend to get my head around it).
Thanks, Syd for raising questions about the markup.
MB>         <link targets="#person #p1"/>
MB>         <link targets="#place #Z10001980"/>
MB>         <link targets="#time #d383873384226"/>
MB> </linkGrp>

this awkward thing is a leftover from an early design stage, when we used records in an <interpGrp> to align
*certain* occurrences of an ID with their category, but this has become redundant now.

  <link type="person-place-time" targets="#p1 #Z10001980 #d383873384226"/>
we didn't want to use this solution because we have to allow for more than one person
and would have to use programming to distinguish if the value is a person a place or a time

    <ptr type="person" target="#p1"/>
    <ptr type="place"  target="#Z10001980"/>
    <ptr type="time"   target="#d383873384226"/>
we will use this for now.

This project extracts prosopographical information from the collected biographies of eminent Buddhist monks
and aims at a GIS like presentation. (I will bring a poster on this to London in November).
We work with the concept of nexus points between person(s), places and time. These nexus points are fairly easy to establish through markup. Events, often touted as a forth category, should be treated in a different manner, we believe.
If anyone knows projects that use TEI markup to construct GIS information I would be grateful for a contact.

all the best


Dr. Marcus Bingenheimer 馬德偉
Director, Library and Information Center 圖書資訊館館長
Dharma Drum Buddhist College 法鼓佛教研修學院 (DDBC)
No. 2-6 Xishihu, Jinshan 20842, Taipei County, Taiwan, R.O.C.
台灣,20842台北縣金山鄉西勢湖2-6號 Tel: +886-2-2498-7171 # 2381