How to declare State Plane coordinates?

[Ben Discoe]

I have a Shapefile which is said to use the following projection:
"Washington State Plane Coordinates, North".

I can use Shapelib (or OGR, i suppose) to load the file, but how do a
construct a OGRSpatialReference with the projection? The online
documentation for OGRSpatialReference::SetStatePlane() has only are the
words "State Plane." So, i dug into the CVS source, and found more: "State
plane zone number, in the USGS numbering scheme."

I dug around more in the source but couldn't locate a set of values for this
'USGS numbering scheme'; there is some related-looking tables in the GeoTiff
code, but AFAICT nothing which describes the values to pass to
SetStatePlane()?

Ideally, i would like to display a list of strings containing the possible
values to the user, so they can inform my program of which State Plane they
have. Does such a table appear anywhere usable in GDAL/OGR?

-Ben