Seriously, what the fuck is this?
The zero in the left axis field does not have that leading line, nor do the two zeros in the dates. The other four zeros have such a line connected to the zero, but in two cases, it’s the horizontal crossbar from the 5, and in two cases, it’s a minus sign. Both horizontal strokes from left to right, leading into the top of the zero.
Spherical and cylindrical corrections would have an explicit sign, positive or negative. If they intended a positive correction, there would be a plus sign.
Those are definitely minus signs.
Three examples of zeroes without the leading marks, two examples where they dragged the crossbar of the 5 into the zero, and two unknowns. Why are you so confident that they aren’t negative signs?