According to IOF material "IOF control descriptions 2004":

Symbol changes:
2.7 stone pile  (3 boulders)            -> 2.6 boulder cluster (2 boulders)
6.4 single tree (triangle with circle ) -> 4.9 distinctive tree (tree)
4.8 copse       (triangle with cross)   -> 4.8 copse (two trees)

Canceled symbols (these symbols are converted to national symbols group nr. 7 in  OORG 9):
1.6  rib   (7.1)
3.5  ditch   (7.2)
3.7  small march (replaces to march)
4.6  felled area   (7.3)
4.10 linear thick (7.4)
6.5  slat lick   (7.5)

New symbols:
5.7   tunnel
5.10  crossing point
5.12  paved area
5.14  pipeline
5.20  statue
5.23  building pass through
5.24  stairway
8.1   low
11.2. beneath

New kind of marked routes:
Taped route beween controls
Mandatory crossing point or points
Madatory passage through out of bounds area

Changes in using of columns:
Symbols from colum D can be placed into column E if you use them together with symbol BETWEEN (G) or CROSSING (F) or JUNCTION (F)
Symbols CROSSING or JUNCTION must be placed into columns F (former E)
 

Symbol conversion table:
//without text means no code change (for ex. 3.8 -> 3.8)

   1.1'  --> '1.4'
  '1.2'  --> '1.5'
  '1.3'  --> '1.6'
  '1.4'  --> '1.1'
  '1.5'  --> '1.2'
  '1.6'  --> '7.1'  // canceled Rib
  '1.7'  --> '1.3'
  '1.8'  --> '1.7'
  '1.9'  --> '1.8'
  '1.10' --> '1.9'
  '1.11' --> '1.10'
  '1.12' --> '1.11'
  '1.13' --> '1.12'
  '1.14' --> '1.13'
  '1.15' --> '1.14'
  '2.1'  --> '2.1'  //
  '2.2'  --> '2.8'
  '2.3'  --> '2.3'  //
  '2.4'  --> '2.4'  //
  '2.5'  --> '2.5'  //
  '2.6'  --> '2.7'
  '2.7'  --> '2.6'  // symbol change: boulder cluster
  '2.8'  --> '2.9'
  '3.1'  --> '3.1'  //
  '3.2'  --> '3.2'  //
  '3.3'  --> '3.3'  //
  '3.4'  --> '3.4'  //
  '3.5'  --> '7.2'  // canceled dicth
  '3.6'  --> '3.7'
  '3.7'  --> '3.7'  // canceled small marsch
  '3.8'  --> '3.8'  //
  '3.9'  --> '3.9'  //
  '3.10' --> '3.10' //
  '3.11' --> '3.6'
  '3.12' --> '3.5'
  '4.1'  --> '4.1'  //
  '4.2'  --> '4.2'  //
  '4.3'  --> '4.3'  //
  '4.4'  --> '4.4'  //
  '4.5'  --> '4.5'  //
  '4.6'  --> '7.3'  // canceled felled area
  '4.7'  --> '4.7'  //
  '4.8'  --> '4.8'  // symbol change: copse
  '4.9'  --> '4.6'
  '4.10' --> '7.4'  // canceled linear thicket
  '5.1'  --> '5.1'  //
  '5.2'  --> '5.2'  //
  '5.3'  --> '5.3'  //
  '5.4'  --> '5.8'
  '5.5'  --> '5.9'
  '5.6'  --> '5.4'
  '5.7'  --> '5.11'
  '5.8'  --> '5.13'
  '5.9'  --> '5.15'
  '5.10' --> '5.5'
  '5.11' --> '5.6'
  '6.1'  --> '5.16'
  '6.2'  --> '5.18'
  '6.3'  --> '2.2'
  '6.4'  --> '4.9'  // symbol change: distinctive tree
  '6.5'  --> '7.5'  // canceled salt lick
  '6.6'  --> '4.10'
  '6.7'  --> '5.17'
  '6.8'  --> '5.19'
  '6.9'  --> '1.16'
  '6.10' --> '1.15'
  '6.11' --> '6.1'
  '6.12' --> '6.2'
  '7.1'  --> '10.2'
  '7.2'  --> '10.1'
  '7.5'  --> '8.2'
  '7.6'  --> '8.3'
  '7.7'  --> '8.4'
  '7.8'  --> '8.5'
  '7.9'  --> '8.6'
  '7.10' --> '8.7'
  '7.11' --> '8.8'
  '7.12' --> '8.9'
  '7.13' --> '8.10'
  '7.14' --> '8.11'
  '8.1'  --> '11.1'
  '8.2'  --> '11.2'
  '8.3'  --> '11.4'
  '8.4'  --> '11.5'
  '8.5'  --> '11.6'
  '8.6'  --> '11.3'
  '8.7L' --> '11.10'
  '8.7U' --> '11.9'
  '8.8'  --> '11.11'
  '8.9'  --> '11.14'
  '8.10' --> '11.8'
  '8.11' --> '11.15'
  '8.12' --> '11.7'
  '9.1'  --> '12.2'
  '9.2'  --> '12.3'
  '9.3'  --> '12.4'
  '9.4'  --> '12.1'
  '9.1a' --> '12.5'