Buick 1993 Roadmaster Owner's Manual page 154

The road signs you see everywhere are coded by color,
shape and symbols. It's a good idea to
know these
-codes
5 . 0
that you can quickly grasp the basic meaning
or intent of the sign even before you have a chance to
read it.
Color of Road Signs
A
f-
P
RED
means STOP. It may also indicate that some
movement is not allowed. Examples are DO NOT
-
.
ENTER and WRONG WAY.
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