[GRASS-user] strategy required

[John Field]

G'day Grass listers,

I'm very new at using Grass, and I'd be most appreciative if someone 
could suggest a strategy to accomplish the following:

I have a map of part of Australia, subdivided into local government 
areas (LGAs).  Both the coastline and the LGA boundaries are vector 
layers, referenced by latitude and longitude.

I want to sample the map at each point on a grid (say at each 0.1 of 
lat and 0.1 of long).  At a sample point I will place a rectangle of 
a given size oriented in a NW-SE direction, with the westernmost 
corner of the rectangle on the sample point.  I then want to 
calculate the proportion of each LGA which is enclosed in the 
rectangle (there may be up to 6 or so).

I'm not familiar enough with Grass to know how best to approach 
this.  I'd be very grateful for any suggested strategies.

With thanks,
John Field
Adelaide, South Australia