Mapping of the MODULE-IDENTITY value

Hi-

I've a question about section 5.6 of RFC 2578, in particular, the second
paragraph which states:

   "Note that it is a common practice to use the value of the MODULE-
   IDENTITY macro as a subtree under which other OBJECT IDENTIFIER
   values assigned within the module are defined.  However, it is legal
   (and occasionally necessary) for the other OBJECT IDENTIFIER values
   assigned within the module to be unrelated to the OBJECT IDENTIFIER
   value of the MODULE-IDENTITY macro."

My question concerns the second sentence:

When is it necessary for the other OBJECT IDENTIFIER values assigned
within the module to be unrelated to the OBJECT IDENTIFIER value of the
MODULE-IDENTITY macro?

If possible, please provide examples.

Regards,

Mark Ellison
Ellison Software Consulting, Inc.