Thank you, I have found eh answer to my question. There is no CS25 requirement to actually have the areas marked. However if you do wish to have them marked then they must be marked correctly. The reference on how they should be marked is in ICAO Annex 6 Part 1 and Part Ops CAT.IDE.A.260. So no legal requirement to have them marked but if you do mark them then how you mark them is specified.