Enum iron::headers::IfRange  
            [-] [+]
        [src]
pub enum IfRange {
    EntityTag(EntityTag),
    Date(HttpDate),
}If-Range header, defined in RFC7233
If a client has a partial copy of a representation and wishes to have an up-to-date copy of the entire representation, it could use the Range header field with a conditional GET (using either or both of If-Unmodified-Since and If-Match.) However, if the precondition fails because the representation has been modified, the client would then have to make a second request to obtain the entire current representation.
The If-Range header field allows a client to \"short-circuit\" the
second request.  Informally, its meaning is as follows: if the
representation is unchanged, send me the part(s) that I am requesting
in Range; otherwise, send me the entire representation.
ABNF
If-Range = entity-tag / HTTP-date
Example values
Sat, 29 Oct 1994 19:43:31 GMT\"xyzzy\"
Variants
EntityTag | The entity-tag the client has of the resource  | 
Date | The date when the client retrieved the resource  |