Coordinate Value Unit Buttons
value buttons allow you to specify the unit of measure for a given coordinate.
When you click a coordinate value unit button, a dialog is presented where
you can select from the appropriate predefined and user-defined units
of measure for the coordinate.
NOTE: You will also notice that
if you specify limited precision for a destination coordinate and convert
the destination value back into the source coordinate system you may not
get exactly the same value you originally entered. Because you can change
the value in any coordinate value edit box at any time, the displayed
value is transformed, not an internal representation of the value. You
should increase the output precision for the coordinates until there is
no significant "round-off" effect.