As far as I'm able to tell, x,y,z co-ordinates are universal -but I'm not going to a-priori assume that until I've tested for differences between WhiteCore and Opensim.
Background and misc notesEdit
This is the co-ordinate system used by opensim. I tested this on 0.8-dev (current March 3, 2014) by sitting on a region set at 0,0,0 and issuing the following command:
load oar --displacement <0,256,0> --merge --forceterrain --forceparcels OARFILE
To my surprise, this put OARFILE north instead of east. As a result, I've made the included diagram for reference. According to the opensim wiki page on Variable regions ( http://opensimulator.org/wiki/Varregion ), you can place standard oars inside of a larger oar by specifying the coordinates with the --displacement, command, which has the syntax:
To place co-ordinates north, change the X number.
To place co-ordinates east, change the Y number.
I have no idea what changing the Z parameter does.
Here is the chart I made as a result of my experiment: