8.1 Legacy Frame-Relay (placement of class)

I understand the correct numbers for this excercise, and how they were calculated.  No problem here.

But I do have a doubt about where I can put the class -- VC vs Interface.

The SolutionGuide places the map-class into the VC's for on all three devices in the frame-relay (R3,R4,R5).

My strategy was:

• R3 (two circuits):  place the map-class into the VC's/DLCI's 
• R4/R5 (one circuit each):    place the class-map on the interface.

This required a little less configuration, and I have not found anything (WB-1) saying that I cannot place legacy MAP-CLASS directly on the interfaces.

Thanks for any clarification on this.