Siemens CP 1515 User Manual page 26

In a stand alone configuration (Figure 2), the Radio Link Module (RLM) will
function as a relay RLM, that will forward the data communication from one
computer to another within the same wireless cell.
This is the quickest and easiest way to set up a small wireless LAN
infrastructure.
The mobile stations communicate via RLM.
26 Industrial Ethernet Wireless LAN RLM Manager, CP 1515 Manager
C79000-G8976-C171-01