diff -r 6da1e81c5652 -r 0ab0d61ccee8 linetypes.py
--- a/linetypes.py	Wed Dec 20 17:25:09 2017 +0200
+++ b/linetypes.py	Thu Dec 21 10:46:41 2017 +0200
@@ -13,6 +13,8 @@
         return 'linetypes.EmptyLine()'
     def textual_representation(self):
         return ''
+    def typename(self):
+        return 'empty line'
 
 class Comment:
     def __init__(self, text, style = 'old'):
@@ -32,6 +34,8 @@
             return '0 ' + self.text
         else:
             return '0 // ' + self.text
+    def typename(self):
+        return 'comment'
 
 class SubfileReference:
     def __init__(self, *, colour, subfile_path, anchor, matrix):
@@ -52,6 +56,8 @@
             self.subfile_path,
         ]
         return ' '.join(ldraw_str(arg) for arg in args)
+    def typename(self):
+        return 'subfile reference'
 
 class BasePolygon:
     def __init__(self, *, colour, geometry):
@@ -73,14 +79,20 @@
 class LineSegment(BasePolygon):
     def textual_representation(self):
         return '2 ' + self.base_textual_representation()
+    def typename(self):
+        return 'line segment'
 
 class Triangle(BasePolygon):
     def textual_representation(self):
         return '3 ' + self.base_textual_representation()
+    def typename(self):
+        return 'triangle'
 
 class Quadrilateral(BasePolygon):
     def textual_representation(self):
         return '4 ' + self.base_textual_representation()
+    def typename(self):
+        return 'quadrilateral'
 
 class Contour(LineSegment):
     def __init__(self, *, colour, geometry, control_points):
@@ -99,3 +111,5 @@
             result += ' '
             result += ' '.join(strings)
         return result
+    def typename(self):
+        return 'contour line segment'