I knew it was possible to edit ones own posts - and for the administrator to delete or move posts from one forum to another - and have taken advantage of the editing capability on a number of occasions when, within minutes of posting I've realised I've made a glaring typo or some other stupid mistake.
I had assumed however that there would probably be some kind of sensible limit on this if only to make it slightly less easy to make a nonsense of an entire thread: perhaps by preventing editing when another person has read the post or at least after replies have been posted.
Apparently not.