What does it mean when a track "straddles north"?
So the problem is that cruising altitudes are assigned based on heading E or W. If the desired track is within a few degrees of north or south, the heading needed to maintain the track could 'straddle' north or south. With some tracks/wind combinations two aircraft flying the identical route at different airspeeds could fall into opposite hemispheres. Traffic in the reverse direction has the same issue, possibly resulting in opposing traffic at the same altitude. So which altitude do you assign/use?