Off hand I think there was an old parameter which didn't do anything much and then I added a new one for the size and position of the use dialog of the node, and more recently the same for the design dialog (not released yet). I can't recall if "frame" is the old one. Try moving the use dialog around or resizing it and you'll find out.
The code for it would be inside of \orpg\gametree\nodehandlers\core.py
Code:
self.frame_size = None
self.frame_pos = None
try:
frame = self.master_dom.getAttribute("frame")
if len(frame):
(sx,sy,px,py) = [int(value) for value in frame.split(',')]
self.frame_size = (sx, sy)
(maxx, maxy) = DisplaySize()
if px < maxx-80 and py < maxy-50:#if it's off screen ignore the saved pos
self.frame_pos = (px, py)
except:
pass
So that looks like frame is the working parameter and it's size X, size Y, pos X, pos Y