[ns] Center of coordinate system in ns (for wireless ad-hoc)

[Andronikos Nedos <nedosa@cs.tcd.ie>]

Hi all,
Just to make sure, what is the center (0,0) of the coordinate system in 
ns? There was another post in the
mailing list but got no reply and the manual does not explicitly 
mentions that. From using ad-hockey
it seems that (0,0) is the top-left corner. Is that so??

Any help appreciated,
    - Andronikos