Having implemented a Policy that uses the "Request Context Variable" to store the URL in the cookie, it does not contain the query string/data.
The orginal URL is http://www.server.com/support/calldetails/pages/default.aspx?Css=~/_layouts/STYLES/RTL/GrayTheme/Css/Main.css&rand=0.5712838824298837
So here the URL is http://www.server.com/support/calldetails/pages/default.aspx and the query data is Css=~/_layouts/STYLES/RTL/GrayTheme/Css/Main.css&rand=0.5712838824298837 and it is this that is not getting stored in the cookie.
Defining "IGNOREQUERYDATA=NO" in the Agent Configuration Object(ACO) resolves this problem and the WHOLE URL including the query data is stored via the REQUEST CONTEXT VARIABLE.
The IgnoreQueryData parameter affects the way Web Agents treat URLs.
A full URL string contains a URI, a hook (?), and some query data, such as:
By default, entire URLs that have been the subjects of requests are cached. Subsequent requests look in the cache for a match. The search for a match fails if requests for the same URI contain different query data. Therefore, ignoring the query data should improve performance.
The IgnoreQueryData parameter affects caching and rule matching:
handled as the same resource
handled as unique resources