diff --git a/sources/io.F90 b/sources/io.F90
index 668b967..d90a1f8 100644
--- a/sources/io.F90
+++ b/sources/io.F90
@@ -36,12 +36,8 @@ module io
 #endif /* HDF5 */
   use timers, only : set_timer, start_timer, stop_timer
 
-! module variables are not implicit by default
-!
   implicit none
 
-! subroutine interfaces
-!
   interface read_snapshot_parameter
     module procedure read_snapshot_parameter_string
     module procedure read_snapshot_parameter_integer
@@ -69,9 +65,7 @@ module io
   end interface
 #endif /* HDF5 */
 
-! timer indices
-!
-  integer            , save :: iio
+  integer, save :: iio
 
 ! MODULE PARAMETERS:
 ! =================
@@ -211,19 +205,16 @@ module io
     integer, dimension(1) :: cd_values = 3
 #endif /* HDF5 */
 
-
 #ifdef HDF5
     character(len=*), parameter :: loc = 'IO::initialize_io()'
 #endif /* HDF5 */
 
 !-------------------------------------------------------------------------------
 !
-    call set_timer('SNAPSHOTS I/O'        , iio)
-
     status = 0
 
-! get module parameters
-!
+    call set_timer('SNAPSHOTS I/O', iio)
+
     call get_parameter("restart_path"     , respath)
     call get_parameter("restart_number"   , nrest  )
     call get_parameter("restart_interval" , hrest  )
@@ -232,14 +223,10 @@ module io
     call get_parameter("include_ghosts"   , ghosts )
     call get_parameter("generate_xdmf"    , xdmf   )
 
-! add slash at the end of respath if not present
-!
     if (index(respath, '/', back = .true.) /= len(trim(respath))) then
       write(respath,"(a)") trim(adjustl(respath)) // '/'
     end if
 
-! check the snapshot format
-!
     call get_parameter("snapshot_format", sformat)
     select case(sformat)
 #ifdef HDF5
@@ -250,8 +237,6 @@ module io
       snapshot_format = snapshot_xml
     end select
 
-! check the restart snapshot format
-!
     call get_parameter("restart_format", sformat)
     select case(sformat)
 #ifdef HDF5
@@ -262,8 +247,6 @@ module io
       restart_format = snapshot_xml
     end select
 
-! check the last available restart snapshot
-!
     if (nrest == 0) then
       test = .true.
       nrest = 0
@@ -273,9 +256,9 @@ module io
       case(snapshot_hdf5)
         do while (test)
           nrest = nrest + 1
-          write(dname, "(a,'r',i6.6,'_',i5.5,'.h5')")                          &
+          write(dname, "(a,'r',i6.6,'_',i5.5,'.h5')") &
                                                 trim(respath), nrest, nproc
-          inquire(file = dname, exist = test)
+          inquire(file=dname, exist=test)
         end do
 #endif /* HDF5 */
       case default
@@ -283,9 +266,9 @@ module io
           nrest = nrest + 1
           write(dname, "(a,'restart-',i5.5)") trim(respath), nrest
 #ifdef __INTEL_COMPILER
-          inquire(directory = dname, exist = test)
+          inquire(directory=dname, exist=test)
 #else /* __INTEL_COMPILER */
-          inquire(file = dname, exist = test)
+          inquire(file=dname, exist=test)
 #endif /* __INTEL_COMPILER */
         end do
       end select
@@ -293,16 +276,12 @@ module io
       nrest = nrest - 1
     end if
 
-! get the compression format and level for XML+binary files
-!
     call get_parameter("compression_format", cformat)
     call get_parameter("compression_level" , clevel)
     call set_compression(cformat, clevel, suffix)
     if (get_compression() > 0) &
       binary_file_suffix = ".bin" // trim(adjustl(suffix))
 
-! get the hash type
-!
     call get_parameter("digest_type", dtype)
     select case(dtype)
 #ifdef XXHASH
@@ -317,8 +296,6 @@ module io
 
     if (status == 0) then
 
-! check if the snapshots should be stored at precise moments
-!
       select case(trim(precise))
       case ("off", "OFF", "n", "N", "false", "FALSE", "no", "NO")
         precise_snapshots = .false.
@@ -327,8 +304,6 @@ module io
       end select
 
 #ifdef HDF5
-! check if the XDMF files should be generated too
-!
       select case(trim(xdmf))
       case ("off", "OFF", "n", "N", "false", "FALSE", "no", "NO")
         with_xdmf = .false.
@@ -336,24 +311,17 @@ module io
         with_xdmf = .true.
       end select
 
-! initialize the HDF5 Fortran interface
-!
       call h5open_f(status)
-      if (status < 0) then
-          call print_message(loc,                                              &
-                       "Cannot initialize the HDF5 Fortran interface!")
+      if (status /= 0) then
+          call print_message(loc, &
+                                "Cannot initialize the HDF5 Fortran interface!")
       else
-
-! prepare the property object for compression
-!
         call h5pcreate_f(H5P_DATASET_CREATE_F, prp_id, status)
         if (status < 0) then
-          call print_message(loc,                                              &
-                       "Cannot create the compression property for datasets!")
+          call print_message(loc, &
+                         "Cannot create the compression property for datasets!")
         else
 
-! detect available compression formats
-!
           cmpstatus = .false.
           if (.not. cmpstatus) then
             call h5zfilter_avail_f(H5Z_ZSTANDARD, cmpstatus, status)
@@ -364,18 +332,14 @@ module io
             if (cmpstatus) compression = H5Z_DEFLATE
           end if
 
-! get the compression_level
-!
           call get_parameter("compression_level", hclevel)
 
-! initialize the compressor
-!
           if (status == 0) then
             select case(compression)
             case(H5Z_ZSTANDARD)
               hclevel = max(1, min(20, hclevel))
               cd_values(:) = hclevel
-              call h5pset_filter_f(prp_id, H5Z_ZSTANDARD, H5Z_FLAG_OPTIONAL_F,    &
+              call h5pset_filter_f(prp_id, H5Z_ZSTANDARD, H5Z_FLAG_OPTIONAL_F, &
                                    cd_nelmts, cd_values, status)
             case(H5Z_DEFLATE)
               hclevel = max(1, min(9, hclevel))