[GRASS-user] v.to.rast questions

[Rich Shepard]

My current topographic vector data file has a column name for the elevation
data, ContourEle. Reading the v.to.rast page there is a use parameter (with
'z' for elevation) and an attribute_column parmater. Because the vector
map's database table does not have a column named 'z', but the one named
'CountourEle' I put both parameters on the command line.

grass told me that I cannot have both, and that using the named elevation
column was not allowed. So I put 'use=z' in the command and the conversion
worked.

How did v.to.rast know that the column named 'ContourEle' was the z value?

Should the manual page explain that the use and attribute_column cannot be
used together for elevation? And, when the attribute_column would be
appropriate?

Regards,

Rich