THE LIQUI MOLY Bathurst 12 Hour field is separated into four classes this year; three in the GT3 category and one for invitational vehicles.
The GT3 structure is based on the drivers in the cars: Each driver is required to be categorised by the FIA as either Platinum, Gold, Silver or Bronze.
Essentially if you're Platinum or Gold you're considered a Professional driver, while Silvers and Bronzes (with some exceptions) are considered 'Amateur' or Semi-Professional.
As such, the class structure works out as follows:
PRO
Three drivers: no categorisation
PRO-AM
Three drivers: Two Platinum, Gold or Silver, one BronzeFour drivers: Two Platinum, Gold or Silver, Two Bronze
SILVER
Three drivers: All SilverFour drivers: Two Silver, Two Bronze
INVITATION
The Invitational class is made up of cars that either don't fit into an existing category or have originally been entered in a class that did not have the numbers to field their own.
That's why the GT4 Mercedes are in that category.
The GT2 KTM X-Bow, MARC Cars Australia entries and the wild SIN R1 are pure invitational entries.
Each Invitational car must have at least one Bronze-ranked driver within their squad.
Invitational class cars are not allowed to lap beneath a 2 minute 06 second benchmark lap time at any point across the weekend.
Dubbed by some the 'Nations Cup Monaro' rule, it's designed to stop one-off specials from knocking off the GT3 machinery that contests for the outright win.
Serious penalties are in place for cars that lap beneath the lap time.