"_parent"is used in the situation where a frameset file is nested inside another frameset file. A link in one of the inner frameset documents which uses
"_parent"will load the new document where the inner frameset file had been.
Want a more complete explanation? Here's the idea in pictures.
For example, this anchor:
<A HREF="bigframe.html" TARGET="_parent">bigframe</A>
produces the link on this page.
If the current document's frameset file does not have any "parent", then
"_top": the new document is loaded in the full window. Note that
"_parent" does not work in a frameset which is merely nested inside another
framset in the same frameset file.
We have discovered that
"_parent" does not work on some versions of Netscape for the Macintosh.