What is the structure of a frameset document as it applies to the DOM?

if you have a frameset with two frames, is the relationship to the window object like this;
window.parent.frame.?

so if you had a nested frameset that looked like this

Code:
<FRAMESET rows="290,*" border=0 noresize> 
  <!-- top frame -->
    <FRAME NAME="top_frame" SRC="video.asp"scrolling=no marginheight=0 marginwidth=0>
  <!-- bottom frame -->
<frameset cols="242,*" frameborder="0" noresize="true">
<frame src="video_nav.asp" name="nav"  scrolling=no marginheight=0 marginwidth=0 bordercolor="#A5A6D2">
<FRAME SRC="test.asp" NAME=test scrolling=auto marginheight=0 marginwidth=0>
</frameset>
</FRAMESET>
what would the path to access the top_frame be?

i thought it would be something like
window.parent.parent.frames.top_frame.document.[whatever here]

this doesn't seem to be correct though...

i know i've seen the DOM for framesets and how they relate to the window object but i can't find any info on it right now...

thanks for any suggestions