Encoding examples (was: Issue 282)

Nilo,

In closing issue 282, I have noticed that the requester has asked 
for examples in Section 3, Part 2 (Encoding).

   "A simple example showing a model graph and one or
   two possible encodings is urgently needed because it
   will make reading and understanding this section a
   lot easier for a lot of people."

It would probably be better if these examples were in the primer 
instead.

What do you think?

Jean-Jacques.