I had this question that has been bouncing around for over 2 years.
Basically, I imagined this molecule:
This molecule, as far as my former (and current) knowledge of nomenclature goes, couldn't be named by me. At first, when I was in about 11th grade, I used to call it ethanoyl chloride, but that's $\ce{CH3COCl}$, not $\ce{CH3COOCl}$. I then thought of chlorine ethanoate, but that's ridiculous too, since chlorine can accomodate the negative charge way better than what ethanoate can.
I looked up a while, and I found out that the $\ce{-OCl}$ group is called a hypochlorite group, that gave rise to my third guess ethanoyl hypochlorite. However, I am not very sure about that either, since ethanoic acid isn't called ethanoyl hydroxide, and methylmethanoate isn't called methanoyl methoxide.
So, what would the "-COOCl" group be called?