2.11BSD/src/usr.sbin/sendmail/cf.named/arpa.ed

ed - arpa.cf << 'EOF'
/S0/
/now delete the local info/
/R\$\*<\$\*\$=w>\$\*/
d
a
R$*%$*<@LOCAL>		$1%$2<@>			handle user%foo@LOCAL
.
w
'EOF'