The Relay "modifies" the input network (all sides except the direction side) and exposes a new network on the output side (the direction side).

The Relay can be set in pass-through mode (on by default). This will make the input network pass as-is to the output network, when redstone mode allows it. This is how the Relay behaves in RS 1.

New in RS 2: If redstone mode allows it, and pass-through mode is disabled, the Relay will start a new output network on the output side. By default, this network will do nothing, but you can choose to pass a few components from the input network to the output network:

• Security rules
• Energy
• Storage resources (everything or specific resources) - also called subnetworking (see #108)
  • Access mode can be set
  • Priority can be set
  • Filter mode can be set (blocklist - allowlist)

Regarding art, new in RS 2: Since networks no longer have a fixed starting point, the Relay is now directional to signify which direction the network signal can be propagated.