OID value: 1.3.6.1.7.1.1.2
OID description:
From RFC-1495...
The following IPMS.HeadingExtension should be generated for all
multipart content-types, with the enumerated value set according to
the subtype:
multipart-message HEADING-EXTENSION VALUE MultipartType ::= id-hex-multipart-message MultipartType ::= ENUMERATED { mixed(1), alternative(2), digest(3), parallel(4) }
URL for further info: http://ds.internic.net/rfc/rfc1495.txt
See also the OID Repository website reference for 1.3.6.1.7.1.1.2