- Something going up a stack from a server to client.
- Something going down a stack from a client to a server.
- A sequence of communication objects organized in a semi-linear sequence
from the application layer at the top to the physical networking layer(s)
at the bottom.
- Something that can be determined using a combination of BACnet objects,
properties and services. For example, discovering the network topology
by using Who-Is-Router-To-Network, or knowing what objects are defined
in a device by reading the object-list property.