They were changed from 6.1 to 6.1.1
They are the templates that control what you see.
editpost.php starts the action, then calles to modifypost.php to complete it. But depending on what you are doing, who you are (admin etc...) and what is in the post (poll etc..) it calls a specific template.
For example, you can't edit the text with a poll. Only close, sticky, delete, move etc...
So the template is different, without the text edit box.
But the form on those templates (the buttons) send back variables to modifypost.php which tell it what you are trying to do.
There was a bug (if I remember) in 6.1 that was fixed for 6.1.1.
You must have had some old files.
