I'm trying to work through the puzzles on regexcrossword.com and I'm finding that it's not clear in its instructions. My understanding of this expression is:
[]
= any combination of the characters within the brackets
*
= 0 or more of the preceding pattern
+
= 1 or more of the preceding pattern
But, I don't see how there's a pattern to be followed at all. What am I missing here?