I engineered an ERD diagram using Barker's notation. The problem was to make a database for system of water pipes where one node is connected to another using a section (pipe), each node can have unlimited number of pipes connected, but the pipe must have only two nodes that it's connected to. Each node that is situated in certain location can have zero or more devices attached.
My other idea was to create one to many relation (section can be assigned to many nodes). Is my diagram correct?
After comments I changed the relations (embedded location in node as well).
Here is the output: