diff --git a/opm/core/transport/reorder/tarjan.h b/opm/core/transport/reorder/tarjan.h
index f331aaed..0492ce9c 100644
--- a/opm/core/transport/reorder/tarjan.h
+++ b/opm/core/transport/reorder/tarjan.h
@@ -20,19 +20,66 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 */
 
+/**
+ * \file
+ *
+ * Simple implementation of of Tarjan's algorithm for computing the
+ * strongly connected components of a directed graph, \f$G(V,E)\f$.
+ * Run-time complexity is \f$O(|V| + |E|)\f$.
+ *
+ * The implementation is based on
+ * "http://en.wikipedia.org/wiki/Tarjan's_strongly_connected_components_algorithm".
+ */
+
 #ifndef TARJAN_H_INCLUDED
 #define TARJAN_H_INCLUDED
+
 #ifdef __cplusplus
 extern "C" {
-#endif
+#endif  /* __cplusplus */
 
-    void
-    tarjan (int nv, const int *ia, const int *ja, int *vert, int *comp,
-            int *ncomp, int *work);
+/**
+ * Compute the strongly connected components of a directed graph,
+ * \f$G(V,E)\f$.
+ *
+ * The components are returned in reverse topological sorted sequence.
+ *
+ * \param[in] nv Number of graph vertices.
+ *
+ * \param[in] ia
+ * \param[in] ja adjacency matrix for directed graph in compressed sparse row
+ *               format: vertex i has directed edges to vertices ja[ia[i]],
+ *                ..., ja[ia[i+1]-1].
+ *
+ * \param[out] vert Permutation of vertices into topologically sorted
+ *                  sequence of strong components (i.e., loops).
+ *                  Array of size <CODE>nv</CODE>.
+ *
+ * \param[out] comp Pointers to start of each strongly connected
+ *                  component in vert, the i'th component has vertices
+ *                  vert[comp[i]], ..., vert[comp[i+1] - 1].  Array of
+ *                  size <CODE>nv + 1</CODE>.
+ *
+ * \param[out] ncomp Number of strong components.  Pointer to a single
+ *                   <CODE>int</CODE>.
+ *
+ * \param[out] work Pointer to a scratch array represented as a block
+ *                  of memory capable of holding <CODE>3 * nv</CODE>
+ *                  elements of type <CODE>int</CODE>.
+ */
+void
+tarjan(int        nv   ,
+       const int *ia   ,
+       const int *ja   ,
+       int       *vert ,
+       int       *comp ,
+       int       *ncomp,
+       int       *work );
 
 #ifdef __cplusplus
 }
-#endif
+#endif  /* __cplusplus */
+
 #endif /* TARJAN_H_INCLUDED */
 
 /* Local Variables:    */