How did Tim's CHM editor do that? I didn't do that deliberately*.
*Unlike the intersection of the B1165 and B1168 with one at 0 and one at -0, to see if it worked, but looks like I made them both -0, with them appearing as 0.000000 on the co-ordinates in the browser (and the trailing zeros are on the files). Fixing that for my little experiment again - seems like every point on the meridian is at -0, rather than 0, but that isn't 360 degrees out.