What is this yellow hinge piece named? Recently, I've been flipping through a scan of the March 1995 edition of the LEGO Mania Magazine. Something in the corner of page 11 caught my eye:



This is the 5th step of the "Flip &amp; Build" segment. I am absolutely puzzled; what is that yellow element that forms that arm? (And by extension, how does it clip to that 1x2 black plate?)

Bear in mind that this is from 1995, so it's no surprise if this piece is discontinued now despite being common back then. Really, what piece is that?
I think this is the yellow element: Hinge Bar 2 with 3 Fingers and Top Stud



And this the black "plate": Hinge Plate 1 x 2 with 2 Fingers and Solid Studs



Both elements are hinges, so they can connect.