Dim Extension Lines on Arc Length- Polar or orthagonal?

[twiceroadsfool]

ACA 2010 or Civil 3D 2010. When i dimension an Arc Length, the extension lines are shooting orthagonally up the page, instead of extending from the centerpoint of the Arc, as i would expect them too. I found the attached image in the help file.

Is this not defeatable? Is it a system variable that im missing somewhere? I have to believe i would have seen this in the past, if we were forced to deal with this with sub-90 degree inscribed arcs.

Thanks in advance.