After entering the realm of economic affairs, Siew--as director-general of the BOFT--first sounded out the business community, then devised the model of indirect trade between Taiwan and mainland China, and suggested to then-President Chiang Ching-kuo that it be implemented.
後來轉到經貿領域，兩岸間接貿易這套模式，就是他在國貿局長任內考訪企業界心聲後，向蔣經國總統建議實施的。