If the specified variable is not in one of the preceding five collections, the Request object returns EMPTY.
All variables can be accessed directly by calling Request(variable) without the collection name. In this case, the Web server searches the collections in the following order:
QueryString
Form
Cookies
ClientCertificate
ServerVariables
If a variable with the same name exists in more than one collection, the Request object returns the first instance that the object encounters.
It is strongly recommended that when referring to members of a collection the full name be used. For example, rather than Request.("AUTH_USER") use Request.ServerVariables("AUTH_USER"). This allows the server to locate the item more quickly.