Attributes for <IFRAME ...>
MARGINWIDTH =integer
MARGINHEIGHT =integer

Usage Recommendation
Don't use it.

MARGINWIDTH and MARGINHEIGHT work much the same as their frame counterparts. MARGINWIDTH and MARGINHEIGHT control the inner margins of the frame.

this code	produces this
<IFRAME SRC="BeaverHabitat.html" WIDTH=250 HEIGHT=250 MARGINWIDTH=1 MARGINHEIGHT=1 > <A HREF="BeaverHabitat.html">Stuff about the Beaver</A> </IFRAME>
<IFRAME SRC="BeaverHabitat.html" WIDTH=250 HEIGHT=250 MARGINWIDTH=30 MARGINHEIGHT=30 > <A HREF="BeaverHabitat.html">Stuff about the Beaver</A> </IFRAME>

These are good attributes to avoid. It's much better to let the browsers display the frame margins as they deem best.

<IFRAME SCROLLING="..."> >>>