Thanks for posting with us, but we removed your submission because we do not allow submissions like "what happened here?", "why is this like this?" or similar.

My guess would be string up lines.

What are those?

All comments must be civil and helpful toward finding an answer.

"My title describes the thing", but for more detail, here goes:

It may have been to hold insulation. Here is the

I'm not sure it's that, as it's even on the floor joists between the main floor and basement where there is no insulation.

Maybe it held up temporary lighting or extension cords during construction.