[rules-users] How to stop rules

[Labuhn]

Hello,

i want to stop the rule engine when some spezial rules fire.
I am working for rules for an online shop.

The Problem (example)
A rule finds out that we cannot put a book into the onlineshop besause
the price is to low, not defined, ....! These rule has a high salience.
When this happends we can stop going on and create an error. In javacode
i can write my one exception and and throw it.
But what can i do in Jboss Rule?

Regards & Thanks
Stefan