dhclient doesn't sent user-class option

[Joshua Schaeffer]

I'm using dhclient 4.3.5 and trying to send my DHCP server the user-class option in IPv6 (option 15). It appears that dhclient is currently not configured to support this option and I was looking for any context surrounding the development of this. I found this in tables.c in the code:

    #if 0
        /* XXX: user-class contents are of the form "StA" where the
         * integer describes the length of the text field.  We don't have
         * an atom for pre-determined-length octet strings yet, so we
         * can't quite do these two.
         */
        { "user-class", "X",            &dhcpv6_universe, 15, 1 },
        { "vendor-class", "X",            &dhcpv6_universe, 16, 1 },
    #endif

What is "form StA"? When it mentions an atom, is this just referencing an atomic type? Is there any roadmap/ETA on when these two codes would be supported?

Thanks,
Joshua Schaeffer