Is it a lug? Is it a head tube? It is all three!

[MrkiMedo]

I have collected few dumpster frames to slice them up for practice tubes, and at the same time to see how are they made. I have two from the same manufacturer, and they have same head tube design. I was scratching my head for some time until I figured out. They have combined tt-ht lug, head tube, and ht-dt lug into one pressed and welded piece. they even went to the effort to make faux lug appearanace on the head tube.

at first all seem normal from outside, although shorelines are suspiciously hard to find:
DSCF1618.jpg
on inside both tt and dt protrude inside and do not lay flat on the ht. Also on closer inspection one can feelthe negative of the HT lug
DSCF1619.jpg
the weld goes on the whole length of the "lugs" and the headtube
DSCF1622.jpg

probably not the finest hour of bicycle industry :)