"INCL_CROSSINGS" which has a value of 1. This returns points where segments cross.The returned geometry is a polyline as that was the simple way of returning a set of points in mapbasic. However, the returns are just a list of points.For example, if a polyline had a clear intersection as in this picture:
then the expression IntersectNodes(obj, obj, 1) would return a polyline of 1 point at the place of intersection.Also note that any polyline can be queried for how many nodes it has with ObjectInfo(obj, 20) .(OBJ_INFO_NPNTS in MapBasic). This will be useful for distinguishing returns that are empty (no self-interesections) from those that do have them.
How can you use this to find the problems?One way would be to create an integer column in your table and then use the Update Column feature to update this new column with this expression