This condition is used to match URI arguments aka query string of Http request messages, for example, in URI http://exaple.com?foo=1&bar=2, the “foo=1&bar=2” is the query string containing URI arguments. In an URI scheme, query string is indicated by the first question mark ("?") character and terminated by a number sign ("#") character or by the end of the URI. The uri_arguments field can be specified as a regular expression(Set match_type to REGEX). For example, “foo=(?<x>\d+)”. It matches HTTP requests whose URI arguments containing “foo”, the value of foo contains only digits. And the value of foo is captured as $x which can be used in LBRuleAction fields which support variables.