For a number of reasons (one of them my lameness) I get extremely confused when it comes to whitespace and newlines in regexps.

Say for example that I want to search for an equal sign (=) followed by any number of whitespace and newline characters.

At certain points in time I have done the following in the belief that these regexps are equivalent:

"=[\s\n]*"
"=[\s-\n]*"
"=[\s]*"
"=[\s-]*"
"=\s*"
"=\s-*"

They are not.

The Emacs regexp docs just manage to confuse me on this one. :-(