When I am kerning and want to cancel the value, I have to go to info box (for which there is no shortcut) and delete it. Kerning back to 0 is of course different from setting it to none, but for me it wouldn’t normally make sense to set the value to 0 unless exception is involved. And in Metrics Machine, 0 is automatically deleted. Would you think it’s reasonable to automatically delete pair value 0 (or implement it in Compress or Clear)?
This could be done for class to class pairs. I’ll have a look.