Can you give me any examle or show me any tutorial/documentation so that I can learn from its basics?
I couldn't find useful information in source codes or I am looking at the wrong place.

From: TSwindells@nds.com
To: rules-users@lists.jboss.org
Date: Mon, 25 Oct 2010 15:39:18 +0100
Subject: Re: [rules-users] matrix style decision tables

There are two type of decision tables in Drools, the standard ones and then matrix ones which are like this format. There are test cases and examples in the source code which should give you some more details on how to use the RuleMatrixSheetListener.

Thomas