How to measure Minimum line spacing for differential pair ?

Hi Kabalee, the function of the differential pair minimum line spacing is to remove drcs when the primary gap or neck gap is lower than the general line to line spacing spacing constraints. If the diff pair gap is set to a value lower than the allowed line to line spacing, then drcs will appear during routing. In this scenario, we must consciously introduce the "minimum line spacing" value as an exemption to prevent drcs on these closely spaced clines. 

Please let me know if this is now clear!

Hi John,

Thanks for your answer. can you add some example here to understand fully

I usually set the "min line spacing" to minimum of neck gap or primary gap. This way we can ensure the differential traces are not routed with less spacing than "min line spacing".