The level controller, uses a triac to switch or dim a light. It is programmed as a Level Controllable Output (DeviceId = 0x0003) or as a Dimmable Light (DeviceId = 0x0101).
The device will be powered from the mains supply, and as such can be in the ON state continuously and therefor also be used as a router.
The power supply should be able to source about 50 mA continuously. This is hardly impossible with the simple, low cost power supply as used for the X10 designs (see schematic), as the capacitor has to be about 2 uF (400V).
The company Power Integrations offers the LinkSwitch(tm) family which enables simple, low cost switching power supplies for these kind of units (see schematic).
The Zigbee unit has to buttons for local control. One for On/Bright and one for Off/Dim.