Seat Tube lug with holes in cross shape: is it unique? for what purpose?

Fifthgrace

Retro Guru
I have a Sedazzari and a contact with what he thinks is a Sedazzari frame. Both have 4 drill holes in cross-shape in the seat tube lug. Is this a distinctive feature of Italian 70s/80s frames or is it specific to a limited number of frame makers? Is it due to the way the lug is made or does it help enable frame construction, or is it to reduce weight?

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