What info must be provided ordering a PCB?

Hello, everybody! I wander if someone can help me to arrange with a PCB
design departament what info must be provided when you order to design a
PCB? (a link to a site,containing such info, would be great). The list of
data inquired by PCB designers can not be too large, in my opinion.
Otherwise, nothing will be left to do for them.:-)
The point is that all people have different opinions and I wanted to refer
to opinion of experineced members of this conference.
Thanks.


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