Canadian practice (AIP RAC 9.20 et sequ) dictates using the term RVR when visibility measured electronically with some form of automatic sensor. Runway lights set at levels 1-3 for 'normal' reporting. If settings of 4 or 5 are used then ATC will give RVR and light setting used.
If Mk I eyeball used then the term is "Ground visibility". How ATC measure this is a closely guarded secret, but may involve runway lights <img src="smile.gif" border="0">
Rgds
CB
[ 06 January 2002: Message edited by: Code Blue ]</p>