That said, you still have unlimited ability to proofread, edit and tweak your posts as long as you wish, the time limit only starts AFTER you hit the "post button" on this forum.
Over on Applefritter, it was NEVER possible for a member to edit the initial post of any give thread. They had problems over there, back in the day, with people editing posts so that threads no longer made any sense at all. It wouldn't surprise me one bit if they've got an editing time limit too.
A Trading Post listing is a thread in its own right, addenda and retractions are the way to modify offerings over time, IMHO.