The proxy class parameter configured in the service definition defines what traffic passes through with the help of the given service. Different services can have different proxy classes configured, even for the same traffic type. For example, a firewall can have a number of services configured to pass HTTP traffic, each with its own, derived and customized proxy class parameter. If these proxy classes are parameterized differently, the corresponding services also behave differently for the same HTTP traffic. A single service can only have a single proxy class value configured, although that proxy class parameter can refer to a stacked proxy setup as well.