diff --git a/qpms/symmetries.h b/qpms/symmetries.h
new file mode 100644
index 0000000..c3bc69a
--- /dev/null
+++ b/qpms/symmetries.h
@@ -0,0 +1,13 @@
+#ifndef SYMMETRIES_H
+#define SYMMETRIES_H
+/* TODO.
+ *
+ * Here will be functions providing point group operations
+ * operating on translation operators and T-matrices
+ * as in tmatrices.py.
+ *
+ * Maybe (much later) also point and space group irrep 
+ * functionality as in symmetries.py.
+ */
+
+#endif // SYMMETRIES_H
diff --git a/qpms/symmetries.py b/qpms/symmetries.py
index edd4d75..c8ccb9c 100644
--- a/qpms/symmetries.py
+++ b/qpms/symmetries.py
@@ -395,6 +395,8 @@ point_group_info = { # representation info of some useful point groups
                  # permutation group generators
                                (Permutation(0,1, size=6)(2,3), # x -> - x mirror operation (i.e. yz mirror plane)
                                 Permutation(0,3, size=6)(1,2), # y -> - y mirror operation (i.e. xz mirror plane)
+                                # ^^^ btw, I guess that Permutation(0,1, size=6) and Permutation(2,3, size=6) would
+                                # do exactly the same job (they should; CHECK)
                                 Permutation(4,5, size=6)       # z -> - z mirror operation (i.e. xy mirror plane)
                                ), 
                  # dictionary with irrep generators
diff --git a/qpms/tmatrices.h b/qpms/tmatrices.h
new file mode 100644
index 0000000..305c3e1
--- /dev/null
+++ b/qpms/tmatrices.h
@@ -0,0 +1,12 @@
+#ifndef TMATRICES_H
+#define TMATRICES_H
+/* TODO
+ * This file will contain declarations of functions providing
+ * a) Mie T-matrix for spherical particle
+ *    i)  using Drude model
+ *    ii) using interpolated material data
+ * b) T-matrix from scuff-tmatrix output, using interpolation
+ */
+
+
+#endif //TMATRICES_H