openpgp_packet_userattribute
    
    
        Implementation of the User Attribute Packet (Tag 17)
 The User Attribute packet is a variation of the User ID packet.  It
 is capable of storing more types of data than the User ID packet,
 which is limited to text.  Like the User ID packet, a User Attribute
 packet may be certified by the key owner ("self-signed") or any other
 key owner who cares to certify it.  Except as noted, a User Attribute
 packet may be used anywhere that a User ID packet may be used.
 While User Attribute packets are not a required part of the OpenPGP
 standard, implementations SHOULD provide at least enough
 compatibility to properly handle a certification signature on the
 User Attribute packet.  A simple way to do this is by treating the
 User Attribute packet as a User ID packet with opaque contents, but
 an implementation may use any method desired.