Hi Stut,
I am referring to the typical 90 day visa for Americans which I would presume is what you're referring to when you say "multiple entry visa". Sorry, my question concerning the days behind cumulative was really a mistake on my part - what I really intended to ask was if the days have to be consecutive or if the "90/180 clock" is suspended when I leave the Schengen Zone. I believe your answer is saying that those 90 days don't need to be cumulative. In that case, do I need to retain some sort of documentation any time I leave the Schengen to show that I wasn't there the entire 90 days since my arrival?
Thank you for your patience and hope this makes sense!