The Source and Target Value expressions can use special characters. These characters (typically ? and *) can be prefixed or suffixed by one or more characters, which filters the source value by that prefix or suffix.
For multiple dimensions, the source dimension is the value brought over and the wild card applies to it alone. the dimensions can be present in a multiple dimensional rule and use wild cards. The prefix/suffix applies only to the source, which equals the target dimension (the dimension on which the rule resides).