The TARGET command  uses;

TARGET="_blank" - Creates a new blank window.
TARGET="_self" - Opens link in same window or frame (default).
TARGET="_parent" - Much like _self but this resets the browser first, removing all frames.
TARGET="_top" - Creates a new window, but not as a child window.

You can also give frames names within the FRAMESET tag, so you can later reference to them. So TARGET could equal;

TARGET="leftFrame"
TARGET="rightFrame"
TARGET="oneWindow"
TARGET="otherWindow"