Much information custom rules

Hi , I didn't manage to find much information about the custom rules in the autoyast file. How they have to be written? I saw that they are shell scripts but what do they have to return ( as a return value of the process ) and actually does it matter . I saw in modules/AutoInstallRules.ycp that they use the stdout for communication with the parent process but what exactly it they have to write on it. I am not very good in this YCP so I am not sure whether I understood everything very well. So does someone have experience with custom rules and have few minutes to explain me. Thanks in advance. I forgot to mention that I use SLES 9 if it does matter. Regards, Pavlin Maslyankov "Tumbleweed E-mail Firewall " made the following annotations on 06/03/05 02:05:37 ------------------------------------------------------------------------------ This e-mail, including attachments, may include confidential and/or proprietary information, and may be used only by the person or entity to which it is addressed. If the reader of this e-mail is not the intended recipient or his or her authorized agent, the reader is hereby notified that any dissemination, distribution or copying of this e-mail is prohibited. If you have received this e-mail in error, please notify the sender by replying to this message and delete this e-mail immediately. ==============================================================================