* Ansgar Burchardt <ansgar@debian.org>, 2011-12-12, 14:44:
Also, §7.1 specifies differently the architecture restrictions for
build relationship fields (Build-Depends, Build-Depends-Indep,
Build-Conflicts and Build-Conflicts-Indep) and binary relationship
fields. According to what is expected for Built-Using, §7.1 could be
updated as well.
Architecture restrictions do not make sense for Built-Using: either a
package was used to built the package or not. In case this differs
between architectures, each binary package has its own (different)
Built-Using list.
But that's not unlike Depends (or other binary relationship fields):
architecture restrictions are allowed in debian/control but not in
binary packages.
And indeed, dpkg-gencontrol does allow architecture restrictions in
Built-Using in debian/control.