Lucky me too that I tested it. lol

Castor sugar is very, very fine white sugar.
It's not icing sugar. Not sure what it would be called there.
I'll look into it. I've seen it with 2 different spellings as well. castor/caster




Well, I guess it's not readily available over there?
Can make your own by processing regular granulated white sugar. Has nothing else in it. Just sugar.