Does stacked electrical equipment in Canada have be flush?

[gchp]

I have two pieces of electrical equipment that I want to mount over each other for a job going to Canada. I have been looking in the Canadian electrical code for the equivialnt to the NEC's "6" rule" stated in 110.26(A)(3) that permits associated equipment to be mounted above or below each other as long as one does not extend more than 6" beyond the front of the other.
I have not found this in the Canadian Electrical code. I found the working space & height in 2-308 but it states nothing about the equipment being flush. Does anyone know if they MUST be flush or does the same 6" allowance apply in Canada?