[R-sig-Geo] add, delete columns in spatial data frame data slot before spRbind

[Murray Richardson]

Hello again users,

I'm having trouble figuring out how to format the data slot in spatial 
SpatialPolygonsDataFrames.  I need to use spRbind to combine polygons 
from different shapefiles but encounter the problem of having different 
numbers of columns, and also non-unique IDs.  If the polygons come from 
different shapefile sources and have different columns in the dbf, what 
is the best way to format them to use spRbind?

Can't seem to find some info on this.

Thanks for any help.

Murray