Superscript plus sign meaning

Question

I have a quick question. What does the superscript plus sign mean here?

= {w ∈ {0,1} : w ∈ (0^+)(1^+)}

Been awhile since I've done these. This is for making a non-deterministic finite automata

Answer 1

0^+

this means that the string w should have atleast one 0, like { 0, 00, 000, .....}

on the other hand

0^*

this means that the string w can contain null character also, like { ∈, 0, 00, 000, ....}