As far as I know, there is no common standard for defining object attributes. It would all depend on what programming language you are using, and what the language's API uses. For instance in your lamp example, should infrared and ultraviolet emissions be an attribute of any lamp object? If your object's intended usage is simple, do you really want to deal with loading huge objects which define every possible attribute? Sometimes all a lamp needs is on/off and wattage.
in reply to (OT) Does anyone know of a common object repository?