Hi Each road has an entry in the NET section that lists the line(s) that make it up. The lines are specified by subdivision number and the index of the line in the subdivision. In turn, inside the RGN section are the actual lines ordered by subdivision/index which contain a pointer back to the NET road-def section. In the broken map these are out-of-step. There are only a small number of subdivisions that are faulty, but most of the roads in the affected subdivs show the problem. I have written a program to cross check between RGN and GET. It is test.check.CheckNet in the display project. It is not immediately obvious why this is happening as the changes that we are suspecting seem to occur well before subdivisions are created. But perhaps I am misreading the code, anything that removes a line after the RoadDef's are created might be the problem. ..Steve