Barnac;
Well, in a story submission, yes. Comments to stories can not be edited by anyone to my knowledge. I regularly correct spelling errors on submitted stories and correct for image sizing and how a story displays such as adding some whitespace to ease reading of the story. Editing for content after comments have been submitted would raise lots of issues so, personally, I don't think that is a good idea.
However, we can delete a comment so it could be resubmitted in a corrected form if needed.
The easiest thing to do if a story you posted has errors is to simply resubmit it in the corrected form with some kind of note or comment that it is the one you want kept and I can delete the previous post. Again, once replies have been posted deleting a comment will delete replies to it [I think] so more "issues" of fairness arise.
We try to be pretty flexible here so let us know what you want and we will do what we can.
Cheers.
TomW