Negative Matching

Each of these match operations can be performed as a “negative match.” That is, the match is successful if the conditions specified are not met. The syntax for the negative match is formed by inserting an exclamation mark '!' before the operation name.

Example:

<match:request-header operation="!name-present" header-name="Referer">

This will cause the match to be evaluated to true if the given header name is not present.