[GRASS5] r.mapcalc: Neighborhood cell index

[Markus Neteler]

Dear developers,

a question related to r.mapcalc's scheme of neighborhood cell index:

In Larson, Shapiro, Tweddale, 1991, "Performing Map Calculations on GRASS
Data: r.mapcalc Programa Tutorial", 3.5. Neighborhood modifiers, p.8.
http://grass.itc.it/gdp/raster/mapcalc.pdf

is written:
"format is map[r,c],..."
"map[1,2] refers to one row below and two columns to the right..."

That means:
 map[y,x] with x positive to "East" and y positive to "South".

For curiousity: Is there a particular reason to have the orientation
pointing positive to South?

Markus