Browser Tab

[Mazherman+75]

I have been curious for a long time to find out what the meaning and or purpose is of some of the items in the Brower Tab, like when in the Object Tools the Browser has some "strange" items, e.g. A BS Commersial, A NY4 RailYard, A OP2, ......etc.

Can somebody please tell me what they are for and do scenario builders use these?