In the 083005 version of the TF's, the landcover classifications for a small 
number of the counties west of the Mississippi were incomplete because 
the BELD dataset on which they were based is incomplete for those counties.  
To avoid this problem,  the 052506rev to the TF's uses the North American 
Landcover Dataset 2000 (NALD 2000) to derive the TFs for States West of 
the Mississippi (WRAP & CENRAP States).  This results in a very small overall 
change in the TF's in the west, but is significant in some counties where the 
BELD was deficient.  The BELD is still used as the basis for the TF's in the 
Eastern States and those TF's are unchanged.