A TDF file does not have to be too involved. The more complicated it is the less useful it may be
simply by making the adoption harder.

This first TDF file is an example of the proposed simplicity.

------------------------------------CoreTags.TDF------------------------------------

The rationale for the Core Tags of GML has been presented in the document:

http://geotech.civen.okstate.edu/w3g/rfc-g103/rfc-g103.htm

Prepared by Jennifer D. McPhail and approved by Mete Oner, this document essentially
proposes that geotechnical data should be organized in a conventional tree structure 
tagged by XML tags specifically derived for this purpose.  The top level of tags are:

<Office>
<Field>
<Lab>

Please refer to the document above for details.

------------------------------------CoreTags.TDF------------------------------------