HTML Attribute for <IFRAME ...>
FRAMEBORDER =1 |0

FRAMEBORDER indicates if the inline frame should have a border around it. 1 (the default) indicates it should, 0 indicates it should not.

This Code Makes This 
<IFRAME 
 SRC="BeaverHabitat.html" 
 WIDTH=150 HEIGHT=150 
FRAMEBORDER=0
 >
<A HREF="BeaverHabitat.html">Stuff 
about the Beaver</A>
</IFRAME>
  
<IFRAME 
 SRC="BeaverHabitat.html" 
 WIDTH=150 HEIGHT=150 
FRAMEBORDER=1
 >
<A HREF="BeaverHabitat.html">Stuff 
about the Beaver</A>
</IFRAME>
  
<IFRAME 
 SRC="BeaverHabitat.html" 
 WIDTH=150 HEIGHT=150>
<A HREF="BeaverHabitat.html">Stuff 
about the Beaver</A>
</IFRAME>
(don't use FRAMEBORDER at all )

<IFRAME MARGINWIDTH="..."> >