A Host_List is made up of one or more hostnames, IP addresses, network numbers, netgroups (prefixed with '+') and other aliases. Again, the value of an item may be negated with the '!' operator. If you do not specify a netmask with a network number, the netmask of the host's ethernet interface(s) will be used when matching. The netmask may be specified either in dotted quad notation (e.g. 255.255.255.0) or CIDR notation (number of bits, e.g. 24). A hostname may include shell-style wildcards (see the Wildcards section below), but unless the hostname command on your machine returns the fully qualified hostname, you'll need to use the fqdn option for wildcards to be useful.

This implies that all Ethernet interfaces use the same netmask, and leaves out FireWire and wireless interfaces. The wording should probably be genericized (perhaps s/ethernet/network/) and clarified for the case where the host has different netmasks.