diff --git a/Cantera/python/Cantera/Interface.py b/Cantera/python/Cantera/Interface.py
index 7641ba23e..798ee4c8a 100644
--- a/Cantera/python/Cantera/Interface.py
+++ b/Cantera/python/Cantera/Interface.py
@@ -7,43 +7,77 @@ from SurfacePhase import SurfacePhase
 from Kinetics import Kinetics
 import XML
 
+__revision__ = "$Id$"
+__log__ = "$Log: "
+
 class Interface(SurfacePhase, Kinetics):    
     """
-    Interface objects represent reacting 2D interfaces between bulk 3D phases. Use function
-    importInterface to build an Interface object from a CTI file definition, rather than
-    calling the Interface constructor directly.
+    Two-dimensional interfaces.
+    
+    Instances of class Interface represent reacting 2D interfaces
+    between bulk 3D phases. Class Interface defines no methods of its
+    own. All of its methods derive from either SurfacePhase or Kinetics.
+
+    Function importInterface should usually be used to build an
+    Interface object from a CTI file definition, rather than calling
+    the Interface constructor directly.
+
+    See: SurfacePhase, Kinetics, importInterface
     """
     def __init__(self, src="", root=None, phases=[]):
-        
+        """
+        src - CTML or CTI input file name. If more than one phase is
+        defined in the file, src should be specified as '<filename>#<id>'
+        If the file is not CTML, it will be run through the CTI -> CTML
+        preprocessor first.
+
+        root - If a CTML tree has already been read in that contains
+        the definition of this interface, the root of this tree can be
+        specified instead of specifying 'src'.
+
+        phases - A list of all objects representing the neighboring phases
+        which participate in the reaction mechanism.
+
+        """
         self.ckin = 0
         self._owner = 0
         self.verbose = 1
 
+        # src has the form '<filename>#<id>'
         fn = src.split('#')
         id = ""
         if len(fn) > 1:
             id = fn[1]        
             fn = fn[0]
-        fname = os.path.basename(fn)
-        ff = os.path.splitext(fname)
+        #fname = os.path.basename(fn)
+        #ff = os.path.splitext(fname)
         
-        # get the 'phase' element
+        # read in the root element of the tree if not building from
+        # an already-built XML tree. Enable preprocessing if the film
+        # is a .cti file instead of XML.
         if src and not root:
             root = XML.XML_Node(name = 'doc', src = fn, preprocess = 1)
-            
+
+        # If an 'id' tag was specified, find the node in the tree with
+        # that tag
         if id:
-            s = root.child(id = id)            
+            s = root.child(id = id)
+
+        # otherwise, find the first element with tag name 'phase'
+        # (both 2D and 3D phases use the CTML tag name 'phase'
         else:
             s = root.child(name = "phase")            
 
-        # get the equation of state model
+        # build the surface phase 
         SurfacePhase.__init__(self, xml_phase=s)
 
-        # get the kinetics model
+        # build the reaction mechanism. This object (representing the
+        # surface phase) is added to the end of the list of phases
         Kinetics.__init__(self, xml_phase=s, phases=phases+[self])
 
 
     def __del__(self):
+        """Delete the Interface instance."""
         Kinetics.__del__(self)
         SurfacePhase.__del__(self)