I've been trying to run the Path Allocation tool with a custom VRMA-VF table to model energy expenditure for travel on foot. The tool will run if I use the built-in vertical factor functions, but hangs indefinitely (most common in ArcGIS 10) or fails with a meaningless error message (most common in ArcGIS 9.3.1) when I use a custom table. I assume I have made an error in formatting the table. The online help (http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//009z000000z9000000.htm) gives an example for building the table, but it is just a copy of the sample table for the horizontal factor. Does vertical factor also need to run from 0 to 180 degrees? If so, to what slope do 0, 90, and 180 correspond?