The Server Response File is the key control mechanism of BIS and BIS-enabled web applications and services. Each web application and service will contain at least one unique Server Response File, identified by the extension .srf. A Server Response File is also sometimes referred to as a stencil, since it acts as a stencil during the process of composing the content of an HTTP response to a request from a User Agent.

Server Response Files are can be HTML files augmented by additional information to control dynamic (program generated) content. In these cases, there are two differences between Server Response Files and regular HTML files:

If Server Response File is used with web services, the Server Response File only contains the necessary tags to allow the Request Handler to route the request to the service program implementing the web service. Care must be taken when creating Server Response Files for web services not to introduce any extra formatting into the response that will confuse the client.