diff --git a/src/flib/pio_types.F90 b/src/flib/pio_types.F90
index 0ef1db08ef2..970c2c83402 100644
--- a/src/flib/pio_types.F90
+++ b/src/flib/pio_types.F90
@@ -153,8 +153,8 @@ module pio_types
   double precision, public, parameter :: PIO_FILL_DOUBLE = nf_fill_double; !< double fill value
 
   enum, bind(c)
-     enumerator :: PIO_rearr_comm_p2p = 0 !< rearranger peer to peer
-     enumerator :: PIO_rearr_comm_coll    !< rearranger collective
+     enumerator :: PIO_rearr_comm_p2p = 0 !< do point-to-point communications using mpi send and recv calls.
+     enumerator :: PIO_rearr_comm_coll    !< use the MPI_ALLTOALLW function of the mpi library
   end enum
 
   !>