ERF ranges can not stradle between positive and negative numbers. The number need to either be all positive going up or down. This is because all measurements are positive measurements, there is never a distance less than 0. In your example below, what you are indicating is the the heel distance, or the bent portion of the lead, can be 2 mils off the pad. If that is the case and you want to find conditions that are great than 2 mils off, that is a different requirements and should be entered into the IDEA site. Please provide the proper reference material to assist in any potential developement.
Thanks for the quick response Max.