If you were surprised that the number of participant types is small in this business network, then you're going to amazed when you see the number of asset types:
Now, this is a sample network–here to teach us about the concepts of business networks, rather than be an exhaustive representation of the world of letters of credit. However, if you think about our example, the whole flow was primarily concerned with just one asset type: the letter.
To be fair, we didn't focus on the goods being transferred–the computers, or the payment. In a real system, these would described as assets. Even so, notice how the number of asset types would still be relatively small. We can create limitless numbers of instances ...