All is documented in help: Originally posted in cdnusers.org by jcteyssier
Suppress equal coordinate: if you have several objects that have same coordinate and that just one can describe all -or several- of them, then just one needed is output.
Suppress leading/trailling zeroes:
You specifies a format for coordinates: say 2.4 in inch so 10 mils will be output as "000010".
If leading is checked, output "10"
If tarilling is checked, output "00001"
This is to minimize gerber file size
I check "leading" and "equal", this is he default behavior.