I would slighty disagree with Waren9, even though the books agree with his statement.
My understanding: if you release the side stick, the aircraft will maintain a 0 vertical acceleration condition.
Otherwise, if it would maintain 1 G, the aircraft would descend as you banked...
Maintaining 0 vertical acceleration as you bank the aircraft will keep your current vertical speed constant (ie level flight if that's what you had at the beginning)
I have heard the terminology of "1G and auto trim for turns" which, in its essence, is the same as my statement but with less "physical / mathematical correctness" if I may
