diff --git a/docs/features.md b/docs/features.md
index cfbec19..bfb80d1 100644
--- a/docs/features.md
+++ b/docs/features.md
@@ -24,3 +24,6 @@ FEATURES / TODO
     - Mortar
 - Modular design
   - E.g. contact formulation can be altered by user
+- Mesh and results format, Xdmf?
+- No scalars but field variables, e.g. no constant 210GPa for steel, we interpolate variable from nodes.
+  - (Constant is a special case of field variable).