API Sisk.Core.Http HttpKnownHeaderNames Copy page Copy as Markdown View as Markdown Copy linkFieldHttpKnownHeaderNames.IfUnmodifiedSinceNamespaceSisk.Core.HttpAssemblySisk.Core.dllIfUnmodifiedSince #The HTTP If-Unmodified-Since header.Used to make a conditional request, allowing the client to specify that the resource should only be returned if it has not been modified since the given date.C# public const string IfUnmodifiedSince = "If-Unmodified-Since"Field Value #string