It basically says that Xenon/HID lights are legal providiing that they meet the standards that new cars with HID/Xenon lights meet:
Therefore a HID headlamp unit sold in the after market should:
1. be type approved to ECE Regulation 98 as a component.
2. when fitted to the vehicle should enable ECE Regulation 48 to be complied with (although no government inspection will take place).
3. Comply with RVLR as far as "use" is concerned.
In practice this means:
1. The headlamp unit (outer lens, reflector, bulb) shall be type approved to ECE 98 and be "e-marked" to demonstrate this. That can only be done by the headlamp supplier - Hella, Valeo etc. who must test the headlamp in an independent laboratory.
2. Once fitted to the vehicle it must have headlamp cleaning and self-levelling (which can be for the headlamp or can be in the vehicle suspension - some expensive estate cars have "self-levelling suspension" and that is adequate). Also the dipped beam must stay on with the main beam.
3. The headlamp must be maintained in good working order, kept clean, and aligned/adjusted correctly like any other headlamp.
Also note that it says the HID/Xenon conversion kits are not legal.