what is the technical word for the marked portion of Formwork?

[archdevil]

Can someone tell me what is the technical word for the marked portion?

 

[HockeyPuck]

In the US, the forms in the picture are typically called "MDO" (Medium Density Overlay) or "HDO" (High Density Overlay) plywood forms. The black surface in the picture is usually made from some sort of resin or polymer coating that is applied to heavy grade plywood. They are more expensive than using regular plywood/lumber forms, but they provide a much smoother finished concrete surface, they typically will last longer and they are easier to maintain than un-coated plywood forms.