At 23:55 -0700 on 04/05/2008, Russ Allbery wrote about Re: current
usage of AAAA implicit MX?:
It's not that it's technically difficult so much as that it's dubious from
a layering perspective, at least from where I sit. It requires I
introduce IPv6-specific code (and hence ifdefs for systems without IPv6
constants and so forth) into an application that otherwise would not need
any and would be entirely stack-agnostic.
OOPS. I was not considering the case where the code was being
tailored at assembly time. Looking at my flow I see only 1 (2 if you
want to ALWAYS set the flag in step 2) place where conditional code
needs to be inserted. This is in step 3 where the Test Flag and IPN
code would only get inserted IF IPv6 support is being generated.