delta coordinates

I am confused with basic understanding of delta configuration.
I am configuring a delta machine and am following the instructions, which refer to xyz coordinates. I understand them to be the carriage heights of the three columns.
I have a vague impression that parts of the procedure mention and use xyz that are really the cartesian coordinates of the nozzle.
so my questions are: am I wrong? do all the configuring instructions by Duet deal only with xyz which are carriage heights?
 if so, is there a way to translate the heights into cartesian nozzle coordinates? how are they called?
 Gcodes from cura for a build are in the cartesian coordinates. where is the forward translation (to carriage heights) done? is there a part in reprap that handles this job?
will appreciate an explanation. thanks.

Normal G1, G0 and other commands use Cartesian coordinates. G1 commands with the H1 or H2 parameters (or the deprecated S1 or S2 parameters) use tower coordinates, and are normally used only in homing files.

dc42, thanks.
how do I move the head to an absolute xy cartesian position ? the dwc allows me only relative movements

@ooly You send G1 Xxxx Yyyy from the console or command input box where xxx/yyy are your absolute positions!
Doug

hi Doug, simple ! thanks