Your observation regarding the DNS Domain Name definition for the A/UX 3.0 manual on Page# 9-4 is correct, it states that users need to modify the following line:
define(DOMAIN, 'DDaux.apple.com')
This line is only available in A/UX 3.0, and is found in the "/usr/lib/sendmail.conf/cf/aux.mc" file. It does not apply for A/UX 3.1.
In A/UX 3.1, the line for "define(DOMAIN, 'DDaux.apple.com')" does not exist in "/usr/lib/sendmail.conf/cf/aux.mc". A/UX 3.1 has the line "DOMAIN(apple-aux)dnl". The word "DOMAIN" is a pre-defined Macro in A/UX╩3.1.
We substitute a pre-defined Macro for "define(DOMAIN, 'DDaux.apple.com')" in A/UX v3.0. With A/UX 3.1, we add the "domain" subdirectory right below "/usr/lib/sendmail.conf" directory hierarchy.
Users should modify the "/usr/lib/sendmail.conf/domain/apple-aux.m4" file, more specifically, substitute their own DNS domain name with "aux.apple.com" in the following example:
DDaux.apple.com
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