not sure if I understand correctly or not, sorry

in xara pro the coordinate settings are based on the bottom left hand corner of the page

so setting the origin[0,0 point] as X 0pix Y 0pix will set the 0 positions of the rulers at the bottom left of the page

setting the origin to X 100pix Y 100 pix will move the ruler 0 positions by 100pix one way
setting X -100pix Y -100pix they move the other way

xara calls setting without - in front increases and settings with - in front decreases
you can choose which way round this applies [left or right, up or down] in the cooridinate direction part of the box

hope this makes sense and helps