I answered over in controlbooth as well
A hyphen in a class name makes for an indented sub class. "Lighting-Incandescent" and "Lighting-Fixtures" will both show up under a "Lighting" header where hierarchical displays are possible. Setting the header to On/Off/Gray will affect all those classes.
Symbol sub classes are not available in the OIP, they are baked into the symbol. Recent libraries have been made this way and I personally believe it is a major mistake! The goal is to be able to turn parts of a symbol on and off, like door swings and label legend tags. There is some control over default classes in Document Settings, but only for whole objects.
There are 2 ways to deal with it if you hate it as much as I do. #1 Delete the sub classes and when the dialog asks about the objects in that class select 'None' or the class you prefer. #2 Rebuild all your libraries. (use method 1, but now they use many files per vendor so it's still some significant work.)
There is much talk of this here in the Vectorworks forums. Some sort of default class import control will likely be in 2017, if you can wait til Sept or Oct.