Does the SVG format used in Inkscape support multiple canvases in a file? After much searching I have been unable to find a way to implement this, so I guess it is not a possibility.

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There's not a way to do it built in, but I think someone wrote an extension or something like that. Let me try to find it and I'll post a link. Or you could also search the forum,(which is where I saw it) if you're in a hurry.

EDIT
Oh, I actually found it pretty quickly: http://sourceforge.net/projects/inkscape-pages/