diff --git a/theories/base.v b/theories/base.v
index 532e7467507e931f056e6a879af54da90ac2bb6a..c30bbe8247d382360c42d1c967335f922583887f 100644
--- a/theories/base.v
+++ b/theories/base.v
@@ -119,8 +119,9 @@ Instance: @PreOrder A (=).
Proof. split; repeat intro; congruence. Qed.
(** ** Setoid equality *)
-(** We define an operational type class for setoid equality. This is based on
-(Spitters/van der Weegen, 2011). *)
+(** We define an operational type class for setoid equality, i.e., the
+"canonical" equivalence for a type. The typeclass is tied to the \equiv
+symbol. This is based on (Spitters/van der Weegen, 2011). *)
Class Equiv A := equiv: relation A.
(* No Hint Mode set because of Coq bug #5735
Hint Mode Equiv ! : typeclass_instances. *)
@@ -1118,6 +1119,8 @@ Notation "½" := half : stdpp_scope.
Notation "½*" := (fmap (M:=list) half) : stdpp_scope.
(** * Notations for lattices. *)
+(** SqSubsetEq registers the "canonical" partial order for a type, and is used
+for the \sqsubseteq symbol. *)
Class SqSubsetEq A := sqsubseteq: relation A.
Hint Mode SqSubsetEq ! : typeclass_instances.
Instance: Params (@sqsubseteq) 2.