This is interesting and something I've suspected for a long while. I remember struggling big-time with older IE versions giving some really strange results when

This is interesting and something I've suspected for a long while. I remember struggling big-time with older IE versions giving some really strange results when doing to perform DOM node manipulations on improperly nested HTML (which in turn often came from copy-pasting from Word), erroneous results that definitively hinted towards DOM tree operations actually happening on flat substrings.