Rules and guidelines

Licence plates here in Trinidad have black letters on a white background......

 

 

and there are also licence plates with white letters and numbers on a black background.

 

 

But I dont believe there are licence plates with black Sharpee letters on a beige background.   

In fact, I think cardboard licence plates are frowned upon ...or maybe not.

This may fall under the difference between a rule and a guideline. 
Having a real licence plate in Trinidad might be just a guideline.
 

Just like the 80 kmh highway speed limit - again, just a guideline. 
A guideline that costs me dearly when I drive back in Canada where it is, yes, a rule.  A very expensive rule.

 

B.