What is a Master Prime Brokerage Agreement??

I was wondering if anyone knows something about a "Master Primer Brokerage Agreement" as it comes up under the ASX's "change of substantial holding" announcement. Attached is an example but I see it often and it generally is with an insto like UBS.

I think it may have to do with Margin lending but the information in section 2 seems always to be blank with no course of sale attached. Maybe I should give our friends at the ASX a call to explain...

regards,
Benwex