The values of the OBJECT IDENTIFIER type correspond to the nodes of object identifier tree, the tree set up to allow unambiguous naming of information objects. So if you need to use some of the tree nodes, you can exploit this type.

The type notation is very easy:

But the value notation is rather complicated. It si possible to use both numeric and symbolic notations, e.g.:

Both given examples describe a telephone number as an attribute defined in object identifier tree.

The only subtyping possibilities are single value and contaned subtype.