Why do my links open new windows instead of updating an existing window?
If you use a name that does not point to a currently available frame, then a new browser window will be opened, and this window will be assigned the name you used. In HTML 4.0, the TARGET attribute value is case-insensitive, so that abc and ABC both refer to the same frame/window, and _top and _TOP both have the same meaning. However, most browsers treat the TARGET attribute value as case-sensitive and do not recognize ABC as being the same as abc, or _TOP as having the special meaning of _top.