A browsing context name is a non-empty string which does not begin with _ (an underscore), and may be specified as the value of name attributes for iframe, object, and frame elements. Browsing context keywords, i.e. one of _self (the default), _blank, _parent, or _top, indicate browsing contexts relative to the current document. Scripts and values of target attributes for a and form elements may indicate browsing contexts by either names or keywords.