[Center of bulidplate and center defined by Cura are not the same.]

what are the reasons for the offset in the center point of the buildplate.

the Second diagram in the picture i have uploaded shows the center point which i calculated by printing a small circle of 1mm radii at [0,0] cordinate in Cura..

[Body Fixed Co-Ordinate System.]

How does Cura decide where the body fixed co-Ordinate system(the one which appears on the body when you are in the move command) is placed?

It appears to symmetric to the part in the X-axis but not in the Y and Z-axis...

[Amount of material extrusion:]

What all parameters does Cura take into consideration when it decides the amount of material it should extrude through the nozzle?

I am trying to write a G-code manually but the print does not come out good as amount of material specified is maybe not right.