diff --git a/src/diagnostics/MOM_sum_output.F90 b/src/diagnostics/MOM_sum_output.F90
index 17427fb80f..8e6cd8b8f1 100644
--- a/src/diagnostics/MOM_sum_output.F90
+++ b/src/diagnostics/MOM_sum_output.F90
@@ -1076,7 +1076,8 @@ end subroutine accumulate_net_input
 !! or it might be created anew.  (For now only new creation occurs.
 subroutine depth_list_setup(G, CS)
   type(ocean_grid_type), intent(in) :: G    !< The ocean's grid structure
-  type(Sum_output_CS),   pointer    :: CS
+  type(Sum_output_CS),   pointer    :: CS  !< The control structure returned by a
+                                           !! previous call to MOM_sum_output_init.
 !  This subroutine sets up an ordered list of depths, along with the
 ! cross sectional areas at each depth and the volume of fluid deeper
 ! than each depth.  This might be read from a previously created file
@@ -1232,10 +1233,11 @@ end subroutine create_depth_list
 
 !> This subroutine writes out the depth list to the specified file.
 subroutine write_depth_list(G, CS, filename, list_size)
-  type(ocean_grid_type), intent(in) :: G    !< The ocean's grid structure.
-  type(Sum_output_CS),   pointer    :: CS
-  character(len=*),      intent(in) :: filename
-  integer,               intent(in) :: list_size
+  type(ocean_grid_type), intent(in) :: G   !< The ocean's grid structure.
+  type(Sum_output_CS),   pointer    :: CS  !< The control structure returned by a
+                                           !! previous call to MOM_sum_output_init.
+  character(len=*),      intent(in) :: filename !< The path to the depth list file to write.
+  integer,               intent(in) :: list_size !< The size of the depth list.
 
 ! This subroutine writes out the depth list to the specified file.
 
@@ -1314,9 +1316,10 @@ end subroutine write_depth_list
 !> This subroutine reads in the depth list to the specified file
 !! and allocates and sets up CS%DL and CS%list_size .
 subroutine read_depth_list(G, CS, filename)
-  type(ocean_grid_type), intent(in) :: G    !< The ocean's grid structure
-  type(Sum_output_CS),   pointer    :: CS
-  character(len=*),      intent(in) :: filename
+  type(ocean_grid_type), intent(in) :: G   !< The ocean's grid structure
+  type(Sum_output_CS),   pointer    :: CS  !< The control structure returned by a
+                                           !! previous call to MOM_sum_output_init.
+  character(len=*),      intent(in) :: filename !< The path to the depth list file to read.
 
 ! This subroutine reads in the depth list to the specified file
 ! and allocates and sets up CS%DL and CS%list_size .