After a bit more experimentation with a smaller project. I think this situation arises from a map made from two survey centrelines (no scraps or maps in the map definition). With maps on M -899999999999999990000000000000000000000000000000000000000000000000000000000 0000000000000000000000000.00 DwarfsDoorElev290Map@ (Dwarfs Door<br>Elevation looking 290 deg) S 749.01 @ () S 732.25 @ () With maps off S -899999999999999990000000000000000000000000000000000000000000000000000000000 0000000000000000000000000.00 @ () So the code needs to test for and either filter out centrelines and maps comprised only of centrelines, or better, correctly determine their name and namespace. Bruce