Your pass number was assigned when you were put on the guest list, and different band members had different levels they could authorize. I'm told that you got a "1" only if two main Beach Boys authorized it, but this is not confirmed. However, at different times and for different reasons, the meaning of the numbers would change. Each venue would have a diagram sheet explaining the meaning of all the passes to the security. Color variations were used if there were multiple shows in a venue, or shows in close proximity, to keep people from reusing passes.
Laminated passes were for people that were at shows a lot throughout the tour, or employees, and the same numbering system applied. They had your picture if you were an employee, or a penned-in name of the type of pass it was--press, promotion, or the initials/number of the performer of which you were a "semi-permanent" guest.