Complement of a Set of Strings in a Language

Question

Suppose $B= \{ 0^n1^m2^{n-m}:\, n\ge m\ge 0 \}$
Is the complement $\overline B = \{ 0^n1^m:\, 0\le n\lt m\}$?

Or is it the universe of all possible strings (including all strings with symbols other than 0, 1 and 2) less $B$?

Answer 1

Complement is all possible strings in the universe that do not lie in $B$. The union of $B$ and its complement should form the universe.