The Ilford manual says:
"The Multigrade 500 system is designed for use with Ilford Multigrade variable contrast papers.
"Prints from graded papers such as Ilford Ilfospeed can be made by using grade 4.5 to give the best compromise between exposure time and image visibility."
I've recently inherited a few sheets of Ilford graded paper but I am yet to try this--new to me--technique. It sounds like a lot of test strips are required, I'd probably end up with no paper left for the print proper.
I assume, too, that they are referring to the native Ilford Multigrade controller with its capacity to dial up grades. They make no distinction between high and low contrast graded papers.
Regards - Ross