diff --git a/app-proto/src/engine.rs b/app-proto/src/engine.rs
index e96ea52..01b5a42 100644
--- a/app-proto/src/engine.rs
+++ b/app-proto/src/engine.rs
@@ -139,8 +139,9 @@ impl ConfigSubspace {
         self.assembly_dim
     }
     
-    // find the projection onto this subspace of the motion where the element
-    // with the given column index has velocity `v`
+    // find the projection onto this subspace, with respect to the Euclidean
+    // inner product, of the motion where the element with the given column
+    // index has velocity `v`
     pub fn proj(&self, v: &DVectorView<f64>, column_index: usize) -> DMatrix<f64> {
         if self.dim() == 0 {
             const ELEMENT_DIM: usize = 5;