The figure below is a syntax diagram of the structure of SharePoint Foundation REST service URIs. You can read more about the SharePoint Foundation REST service here.

Syntax diagrams are a useful way of illustrating linear data structures. Things like:

• REST URI composition
• API signatures
• JSON, OData, or other XML-based data notation

You can find out more about syntax diagrams at this Wikipedia entry, see some examples using JSON here, and see some more examples in the OData specifications.