diff --git a/include/numerics/numeric_vector.h b/include/numerics/numeric_vector.h
index c89efa28887..0ac3de4cec7 100644
--- a/include/numerics/numeric_vector.h
+++ b/include/numerics/numeric_vector.h
@@ -717,10 +717,13 @@ class NumericVector : public ReferenceCountedObject<NumericVector<T>>,
   }
 
   /**
-   * Fills in \p subvector from this vector using the indices in \p
-   * rows.  Similar to the \p create_submatrix() routine for the
-   * SparseMatrix class, it is currently only implemented for
-   * PetscVectors.
+   * Fills in \p subvector from this vector using the indices in \p rows.
+   * Similar to the \p create_submatrix() routine for the SparseMatrix class, it
+   * is currently only implemented for PetscVectors. The boolean parameter
+   * communicates whether the supplied vector of rows corresponds to all the
+   * rows that should be used in the subvector's index set, e.g. whether the
+   * rows correspond to the global collective. If the rows supplied are only the
+   * local indices, then the boolean parameter should be set to false
    */
   virtual void create_subvector(NumericVector<T> & ,
                                 const std::vector<numeric_index_type> &,