If you use the HttpResponse.AppendHeader(string, string) method to send cache-specific headers and at the same time use the cache object model (HttpResponse.Cache) to set cache policy, HTTP response headers that pertain to caching (Cache-Control, Expires, Last-Modified, Pragma, and Vary) might be deleted when the cache object model is used. This behavior enables ASP.NET to maintain the most restrictive settings. For example, consider a page that includes user controls. If those controls have conflicting cache policies, the most restrictive cache policy will be used. If one user control sets the header "Cache-Control: Public" and another user control sets the more restrictive header "Cache-Control: Private" via calls to HttpCachePolicy.SetCacheability(HttpCacheability), then the "Cache-Control: Private" header will be sent with the response.

For a list of standard HTTP/1.1 headers, see section 14, "Header Field Definitions," in the tp://go.microsoft.com/fwlink/?LinkID=73147 specification on the World Wide Web Consortium (W3C) Web site.

Namespace: System.Web
Assembly: System.Web (in System.Web.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0