You can use an iframe for internal (same site) pages as well, especially useful for scrollable content within a short parent page.
Though layers may suit the OP much better.
HTML Code:
<iframe name="myframe" src="main.htm" width="100%" height="100%" frameborder="0" scrolling="auto" name="xara_iframe" ><p>Your browser does not support iframes.</p></iframe>
Links to other pages from the first page can be directed to the iframe via the 'link' tab in Web Properties and by making certain that the link target is set to the iframe name in 'Open Link'
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