If layer Default does not exist,
“Message: Could not find Layer with ID 00000000-0000-0000-0000-000000000000” is thrown for rs.IsLayer(…) such as when using this script (from Rhino IronPython Help):
import rhinoscriptsyntax as rs layer = rs.GetString("Layer name") if rs.IsLayer(layer): print "The layer exists." else: print "The layer does not exist."
This does not occur in V5. I also haven’t found other layer names that do this in V6.