+Any following words on the same line are taken to be a list of
+acceptable IP addresses for that client. If there are only 3 words on
+the line, or if the first word is "-", then all IP addresses are
+disallowed. To allow any address, use "*". A word starting with "!"
+indicates that the specified address is \fInot\fR acceptable. An
+address may be followed by "/" and a number \fIn\fR, to indicate a
+whole subnet, i.e. all addresses which have the same value in the most
+significant \fIn\fR bits. In this form, the address may be followed
+by a plus sign ("+") to indicate that one address from the subnet is
+authorized, based on the ppp network interface unit number in use.
+In this case, the host part of the address will be set to the unit
+number plus one.
+.LP