Where has my Mark Edge Seam button gone? I'm using blender 2.79 and have not modified any of its code, but for some reason I have to use the space bar and search for "Mark Seam" in order to use this function. I should not that I don't see it in blender 2.8 either. Am I missing something? I thought it was always under the Edge's Menu!

Menu: Mesh ‣ Edges ‣ Mark Seam/Clear Seam is gone!

Has anyone had this problem, or know how to fix it?
I'm not sure if I'm doing this right. But as @Robin Betts pointed out. The Mark Seams function has moved to the Edge Data Sub-menu.

Thank you @Robin Betts !