diff --git a/.gitignore b/.gitignore
index 0756691e..2cb7d551 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 *.swp
 doc
+lib
diff --git a/src/adaptors/rotmat.rs b/src/adaptors/rotmat.rs
index f0dcb42b..c2f61a85 100644
--- a/src/adaptors/rotmat.rs
+++ b/src/adaptors/rotmat.rs
@@ -7,18 +7,24 @@ use traits::dim::Dim;
 use traits::inv::Inv;
 use traits::transpose::Transpose;
 use traits::rotation::Rotation;
+use traits::delta_transform::DeltaTransform;
 use dim1::vec1::{Vec1, vec1};
 use dim2::mat2::{Mat2, mat2};
 use dim3::mat3::{Mat3, mat3};
 use dim3::vec3::{Vec3};
 
-// FIXME: use a newtype here?
 #[deriving(Eq)]
 pub struct Rotmat<M>
 {
   priv submat: M
 }
 
+impl<M: Copy> Rotmat<M>
+{
+  fn submat(&self) -> M
+  { self.submat }
+}
+
 pub fn rotmat2<T: Copy + Trigonometric + Neg<T>>(angle: T) -> Rotmat<Mat2<T>>
 {
   let coa = Trigonometric::cos(angle);
@@ -130,8 +136,13 @@ impl<V, M: LMul<V>> LMul<V> for Rotmat<M>
   { self.submat.lmul(other) }
 }
 
-impl<M: Copy + Transpose>
-Inv for Rotmat<M>
+impl<M: Copy> DeltaTransform<M> for Rotmat<M>
+{
+  fn delta_transform(&self) -> M
+  { self.submat }
+}
+
+impl<M: Copy + Transpose> Inv for Rotmat<M>
 {
   fn invert(&mut self)
   { self.transpose() }
diff --git a/src/adaptors/transform.rs b/src/adaptors/transform.rs
index b820a12e..b2d90413 100644
--- a/src/adaptors/transform.rs
+++ b/src/adaptors/transform.rs
@@ -6,15 +6,17 @@ use traits::inv::Inv;
 use traits::rotation::Rotation;
 use traits::translation::Translation;
 use traits::transpose::Transpose;
+use traits::delta_transform::DeltaTransform;
 use traits::workarounds::rlmul::{RMul, LMul};
 
 pub struct Transform<M, V>
 {
-  submat   : M,
-  subtrans : V
+  priv submat   : M,
+  priv subtrans : V
 }
 
-pub fn transform<M: Copy, V: Copy>(mat: &M, trans: &V) -> Transform<M, V>
+pub fn transform<M: Copy, V: Copy>(mat: &M, trans: &V)
+-> Transform<M, V>
 { Transform { submat: *mat, subtrans: *trans } }
 
 impl<M:Dim, V> Dim for Transform<M, V>
@@ -95,6 +97,12 @@ Rotation<V> for Transform<M, V>
   }
 }
 
+impl<M: Copy, V> DeltaTransform<M> for Transform<M, V>
+{
+  fn delta_transform(&self) -> M
+  { self.submat }
+}
+
 impl<M:Copy + Transpose + Inv + RMul<V>, V:Copy + Neg<V>>
 Inv for Transform<M, V>
 {
diff --git a/src/nalgebra.rc b/src/nalgebra.rc
index 6e5ec61a..4a9e04d7 100644
--- a/src/nalgebra.rc
+++ b/src/nalgebra.rc
@@ -48,6 +48,10 @@ mod traits
   mod norm;
   mod rotation;
   mod translation;
+  mod delta_transform;
+  mod vector_space;
+  mod ring;
+  mod division_ring;
 
   mod workarounds
   {
diff --git a/src/tests/mat.rs b/src/tests/mat.rs
index fca18dd0..290615fe 100644
--- a/src/tests/mat.rs
+++ b/src/tests/mat.rs
@@ -4,8 +4,6 @@ use core::num::{One, abs};
 use core::rand::{random};
 #[test]
 use std::cmp::FuzzyEq;
-// #[test]
-// use ndim::nmat::NMat;
 #[test]
 use traits::inv::Inv;
 #[test]
@@ -20,8 +18,6 @@ use dim2::mat2::Mat2;
 use dim3::mat3::Mat3;
 #[test]
 use adaptors::rotmat::Rotmat;
-// #[test]
-// use traits::dim::d7;
 
 // FIXME: this one fails with an ICE: node_id_to_type: no type for node [...]
 // #[test]