Some responses below... On 4/13/07, Arjun Dhar <dhar_ar(a)yahoo.com&gt; wrote: "from" means you can call some/any logic only when needed - and only once the "from" node is checked - so its as lazy as possible. You could kind of do the same with eval() for very simple cases I guess, but also, with from you can reason over it as if the data was in working memory. Q2. I use Decision Tables extensively; how do I use 'From' in a decision No thoughts on how it would integrate there, off the top of my head I can't see how it would be used there. Open to any ideas. Q3. When executing PL/SQL logic, the data is at the database itself and so yes, although it would generally be a SQL query. 3.1. If we decide to abstract the logic to rules and fetch data from the Possibly - in some cases sure. In other cases, it may be easier to use the rete engine, and then use the database to filter large amount of data that aren't facts. 3.2. Since most mainstream applications use external data, when we talk I guess you would need to try out in specific cases. Sometimes it may be a tradeoff for speed versus flexability and expressability. ... The above are pratical issues that am sure everyone would ask.