.IR key .
.hP \*o
An occurrence of
-.BI $[ host ]
+.BI $ flags [ host ]
is replaced by the IP address of the named
.IR host .
Note that
.I host
may itself contain
.BI $( key )
-substitutions.
+substitutions. The
+.I flags
+consist of zero or more of the following characters:
+.RB ` 4 '
+looks up the
+.IR host 's
+IPv4 address(es);
+.RB ` * '
+returns all of the found addresses, separated by spaces, rather than
+just the first one.
.PP
There is a simple concept of
.I inheritance