For a standard ACL, a source IPv4 address and an optional wildcard or IPv6 address and length are specified for the rule. For an extended ACL a source and destination IP address and wildcard are specified for the rule. In the case of an IPv4, Source and destination wildcards provide an inverted mask (specifies the don‘t care bits as 1s). 0.0.0.0 specifies an exact match. An any option is available. The any option is short hand for 0.0.0.0 255.255.255.255.