1 files changed, 10 insertions, 0 deletions
diff --git a/lib/kernel/liturgical_day.mli b/lib/kernel/liturgical_day.mli
index 939f8f5..be17d73 100644
--- a/lib/kernel/liturgical_day.mli
+++ b/lib/kernel/liturgical_day.mli
@@ -8,6 +8,16 @@ type ('s, 'r) t = {
           places for them to disagree *)
   observed : 'r Celebration.t;
   commemorations : ('r Celebration.t * Precedence.privilege) list;
+      (** The LOW MASS admitted set (RG 111(b)/(c)/(d) -- {!Precedence.rules.admit}'s
+          own wider caps). Not named [low_mass_commemorations]: this field
+          predates the sung/low distinction and every existing reader
+          ([emit], the differential/oracle layers, {!Record}) already reads
+          it under this name, so renaming it would be a needless breaking
+          change for a doc clarification alone. The SUNG-Mass equivalent
+          (RG 111(a): at most one commemoration, and it must be privileged)
+          is {!Precedence.sung_mass_commemorations}, a pure derivation over
+          this same list -- see its own citation for why it is a function,
+          not a second stored field. *)
   transferred_in : 'r Celebration.t option;
       (** arrived here from an impeded day *)
   transferred_out : ('r Celebration.t * Date.t) list;