3.2.5.5 If Header Modification

A server compliant with the WebDAV Protocol: Microsoft Extensions MAY be compliant with the If header specification in [RFC2518] section 9.4.<27>

Whether or not a WebDAV Protocol: Microsoft Extensions server is in compliance with If header semantics as specified in [RFC2518] section 9.4, a WebDAV Protocol: Microsoft Extensions server MUST allow for an If header of the form specified in section 3.1.5.5 and perform the checks specified in [RFC2518] required to honor the If header.<28>