Scutum Bracing

[Primvs Pavlvs]

I have built several shields not scutum, and clipus styles, and a few medieval shields. I am curious since the Fayam (sp) does not seem to show any traces of having any braces on the back. Would it be incorrect to make scuti without the bracing? I know most of the reproductions I have seen all have the braces. Does this come from the Dura shields? or is there others with it that I do not know about?

Thanks,

Primvs