create a new datum conversion

[dpa-ig]

Someone know how to create a new datum conversion, but it has six parameters...It is a similarity transformation i want to put in a new configuration.

following data are:

centroid: x=453106; y=7076452

traslation in X=-179.2

traslation in Y=-386.302

scale in ppm= -832.154

ang in rad = 2.5*10^6

thanks

[arturopolanco]