mapscript API shapfileObj units

[Kralidis,Tom [Burlington]]

Hi,

We have a script which utilizes the new mapscript geos functionality by
applying a buffer to each shapeObj within a shapefileObj to output a new
dataset.

My question is I would like to know the units of shapefileObj (or
shapeObj).

The mapscript API has layerObj->{units} as a property, but I am not
working within the layerObj context (i.e. I am not working on mapfiles,
just datasets).

Any idea on how to fetch this info from the mapscript API without
layerObj?  I've skimmed through
http://mapserver.gis.umn.edu/docs/reference/mapscript/index_html as part
of my investigation, but didn't find anything else (or course I may have
glossed over something -- happens to me often!).

Thanks

..Tom