Help:Extension:DynamicFunctions

As taken directly from the extension page on MediaWiki:

Functions
This module defines four functions: arg, ip, rand, and skin. All of these functions operate in constant time.

#arg:
The #arg function returns the value of the given URL argument. The syntax is:

.

The default parameter is optional; if defined, it is returned when the argument does not exist.

Thus, instead of including a page for given parameter values, this allows linking to a page for given parameter values. Syntax for linking: external link style with zero or more times "&parameter name=parameter value" added to the URL. The link can be to the same page with different parameter values, or to a different page. In the former case the new values can depend on the old ones.

#ip:
The #ip function returns the IP address of the current user. No arguments are required. This should correspond to the IP in the last line of Special:Version.

#rand:
The #rand function returns a random integer value. The syntax is:


 * 1) rand returns a value between a and b, inclusive.  If b is omitted, #rand returns a value between 1 and a (hence,  emulates a dice roll).

The function is PHP function mt-rand.

#skin:
The #skin function returns the name of the current skin. No arguments are required.