This report is nearly 15 years old, however it does highlight the need for pilots to know what Visual Docking Guidance System (VDGS) is provided on parking stands and how to interpret them.
If VDGS is provided and it's not switched on then proceed on to stand at your peril, therefore best to hold off and request a marshal.
If VDGS is provided and it is not understood then again hold off and request a marshal.
Airports should provide accurate detail in the AIP on the VDGS or not provided on parking stands so pilots know what to expect when allocated stands. Not sure though if pilots capture this information in their briefings.
If in doubt hold off stand and request marshal.