I am creating a new page format, that uses an Architectural D-size paper, and a custom border that is somewhat ornamental  But, I can't figure out how to get the boarder centered on the page. 

There doesn't seem to be an origin to snap to.  I can just eye-ball the center, but I think draftsmen, by their very nature, hate eye-balling the position of a drawing.

All the videos or tutorials on custom sheet formats that I have come across, all start with an existing format of an ANSI size, and leave the default border in place.

-Joe