isIp
Takes a single argument, a string, and returns:
- "6" if it is a valid IPV6 address
- "4" if it is a valid IPV6 address
- empty string if it is neither.
When applied to {{PAGENAME}}, this helps determine whether a template is being placed on an anonymous user page/user talk page or not, as used in Template:AfC talk: {{#if:{{IsIPAddress|{{PAGENAME}}}}|I'm on an anonymous IP user or user talk page|I'm on some other page}}
isIpV6
Returns 1 if the given argument is a valid IPv6 address, else 0.
isIpV4
Returns 1 if the given argument is a valid IPv4 address, else 0.