# Coordinate Systems

xyscan uses 2 coordinate systems:

Local Coordinates
  These are essentially the screen coordinates of the window in which the plot is displayed. The units are screen pixel. The upper left corner of the plot is defined as the origin (0,0) of the plot. x coordinate increases to the right, y increases downwards. They are displayed on the top of the Coordinate Display window once a plot is loaded.
Plot Coordinates
  These are the coordinate of the plot/data points you want to scan. In order to transform local coordinates into plot coordinates, xyscan needs markers to be set along the axis. The user has to provide the position of the markers in plot coordinates.