Any language has areas where the usage is uncertain. English, it seems to me, has a lot of uncertain areas. Just to give two examples:
none, singular or plural?
dice, noun, singular and plural form?
I discovered such things a long time ago and created a name for me "grey zones", but I never had time to collect such things in a more systematic way. I'm only just now beginning with such a collection. Grey zones are grammar points were grammars have difficulties and tell long and complicated stories instead of saying first of all: It's a grey zone.
My question: Is there a name in English grammar or linguistics for my personal term grey zone? And are there studies about such uncertainties? I think they would fill a small dictionary, especially if one considers different usage of BrE and AmE.