- Supported PointSymbol
     * Bar              - Bar
     * "1O"             - Point
     * "6O"             - Triangle Left
     * "7O"             - Triangle Right
     * "8O"             - Triangle Down
     * "9O"             - Triangle Up
     * "TL"             - Triangle Left (new alias)
     * "TR"             - Triangle Right(new alias)
     * "TD"             - Triangle Down (new alias)
     * "TU"             - Triangle Up   (new alias)
     * "BX", "SQ"       - Square Box    (new)
     * "RH"             - Rhombus       (new)
     * "PL", Plus       - Plus          (new)
     * "TI", Times      - Times         (new)

実装の詳細は、以下を参照

http://afsad1.kek.jp/viewvc/viewvc.cgi/oldsad/src/tfcanvasclip.f?view=log&r1=1.52