In regular expressions, "?=" is _not_ correct -- "?" is a quantifier, I think you mean "(?=...)" -which must include the parens

[ckollars]

In http://www.w3schools...exp_nfollow.asp (and elsewhere), ?= is listed as a "quantifier", but this is not accurate. ?= is neither called a "quantifier", nor even works. (The "quantifier" is the single character ?, it means apply the quantity "0 or 1 times" to whatever's at left.) Your "reference" seems to be incorrect here. What ?= really is is part of the regular expression construct (?=...) (note the syntax is incomplete and doesn't work without the required parens). (A parallel regular expression construct, for "not equals" rather than "equals" is (?!...)