In this case "Revenue Customer" relates to travel paid with using Money or points/miles awards rather than Staff travel or ID90 type travel.
See this *A thread:
http://www.flyertalk.com/forum/star-...l#post12308642
Also see StarAlliance Guide linked to below¹, page #141:
Revenue ticket/customer: All customers excluding airline staff. Customers travelling on discounted fares, frequent flyer award tickets or upgrades are considered revenue customers and are included as revenue customers. Airline employees flying on free or service charge tickets, or Industry Discount e.g., ID50, ID75, ID90) tickets are not considered revenue customers;
¹
http://www.starallianceemployees.com...b.pdf#page=141 (Be aware this file is 7Mb)