If-Unmodified-Since
| If-Unmodified-Since |
The If-Unmodified-Since header is the twin of the If-Modified-Since header. Including it in a request makes the request conditional. The server should look at the date value of the header and return the object only if it has not been modified since the date provided. Chapter 7 discusses conditional requests in detail.
Type
Request header
Basic Syntax
If-Unmodified-Since: HTTP-date
Example
If-Unmodified-Since: Thu, 03 Oct 1997 17:15:00 GMT