as-set and origin as usage

To protect your privacy, remote images are blocked in this message. Display images Hello everybody, A few days ago I intended a RIPE RPSL training. Now I'm writing a summary for my colleagues and there something I don't remember perfectly, it's about the as-set object. Using an as-set object, I can either start its name with an origin as or directly put the name (ex. AS-Customers). Under which circumstance should I specify the origin AS? Thank you very much for your help, Regards,