Sets the ETag HTTP header to the specified string.
Assembly: System.Web (in System.Web.dll)
The ETag header is a unique identifier for a specific version of a document. It is used by clients to validate client-cached content to avoid requesting it again. Once an ETag header is set, subsequent attempts to set it fail and an exception is thrown.
is introduced in the .NET Framework version 3.5. For more information, see .NET Framework Versions and Dependencies.