when all men (and women) speak the same language (USA take note) then plain English will be plain to all. Till then consider the sign we now use at roadworks with traffic lights.

"When red light shows wait here" has replaced :

"Wait while red light shows" because :

OOP north (Lancs Yorks) "while" means "until" to many people. But not to Londoners who order/purchase the signs.

Je ne parle plus Yokshire.