From my experience (and checking through a CAM house that represents many fab partners, and the Valor user group too) REMOVE the board outline from copper and silkscreen layers, but they need it on at least one layer, so the SolderMask layer is a natural choice. Sometimes they will even expand this line so the mask doesn't go all the way to the edge of the board. 
I also provide it on the paste screen layers because sometimes only those specific layers are sent to the screen manufacturer (without all the others) and they want to see it. 

So, put it on the Paste and Mask layers, remove it from everything else. If your fabricator doesn't want it on the Mask layers, then you will have to provide it as a separate file.

My answers are based on research I did for this article about the CAM process:
http://www.frontdoor.biz/HowToPCB/HowToPCB-CADtoCAM.html

hope that helps,
Jack


On Tue, 31 Jul 2012 09:55:26 -0500, Barbara Burcham <[log in to unmask]> wrote:

>I have run up against the question of putting the board outline on each
>gerber file. One fabricator who needs it on at least on file.
>What do fabricators need regarding this?
>What about board outline on the stencil gerbers for the Stencil Makers?
>
>Regards,
>Barbara Burcham, CID
>Sr. PCB Designer
>
>
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