Several comma-separated tags will be considered as logical AND between them. You can also use semicolon for logical OR. AND has a priority over OR and you cannot use parentheses for logical grouping. Asterisk (*) within a tag will be regarded as a mask for "any string".
So you want to write your own extensions? This is the first in a series of articles to help you use the Cotonti modules and plugins system. Each article in the series will discuss a specific subject concerning plugin development.