In message <199702131805.TAA21033@vader.runit.sintef.no> you write:
>#define IGMP_MTRACE_REPLY               0x1e  /* traceroute reply      */
>#define IGMP_MTRACE_QUERY               0x1f  /* traceroute query      */

Uh, that was a decision that whomever ported the 3.5 multicast kernel
to NetBSD made, I guess.  I'll put in #ifdef __NetBSD__, but it seems like
a shame.

>Oh, yes, BTW, the usage message in mtrace 5.1's source code
>hasn't been updated with the -P option.

Thanks, I'll update it.

  Bill