4.0 XDCR Filtering regex ^ hat

http://developer.couchbase.com/documentation/server/4.0/xdcr/xdcr-reg-expressions.html

The page states:

^ This is the "not" character, therefore [^0-9] matches against any character that is not a digit.

that isn't entirely true and could be confusing, we use the javascript regex model, looking at the mozilla regex docs a hat character "^" has 2 meanings and the "not" attribute is the least common attribute.

https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions
states:
Matches beginning of input. If the multiline flag is set to true, also matches immediately after a line break character.

For example, /^A/ does not match the 'A' in "an A", but does match the 'A' in "An E".

The '^' has a different meaning when it appears as the first character in a character set pattern. See complemented character sets for details and an example.