# Unit test: calloutlist.004

This image map uses `calspair`

coordinates. The
CALS pair coordinate system measures rectangles from the lower-left
coordinate to the upper-right coordinate as a percentage of the size
of the image. Each coordiante is multiplied by 10,000 to make an
integer. For example, a coordinate of 20.25% is represented as
2025. If your image is a square, the upper right quadrant of
that square can be identfied with the CALS pair coordinates
`5000,5000,10000,10000`

.

The HTML coordinate system measures rectangles from the upper-left
coordinate to the lower-right coordinate in pixels. If the square
has a side-length of 200 pixels, the coordinates that correspond to the
upper right are `50,0,100,50`

.