across=1应该是说legend中的symbol图标分1列显示的，将这个改为2，3都可以的，你在运行下就明白了
mode没见过，同求解

对      

mode好像是指定图例的排放方式

喔，刚查了下，对了，看你名字，华科的？
http://support.sas.com/documenta ... .htm#legendchap.htm

MODE=PROTECT | RESERVE | SHARE

    specifies whether the legend is drawn in the procedure output area or whether legend elements can overlay other graphics elements. MODE= can take one of these values:
    PROTECT        

    draws the legend in the procedure output area, but a blanking area surrounds the legend, preventing other graphics elements from being displayed in the legend. (A blanking area is a protected area in which no other graphics elements are displayed.)
    RESERVE        

    takes space for the legend from the procedure output area, thereby reducing the amount of space available for the graph. If MODE=RESERVE is specified in conjunction with OFFSET=, the legend can push the graph off the graphics output area. RESERVE is valid only when POSITION=OUTSIDE. If POSITION=INSIDE is specified, a warning is issued and MODE= value is changed to PROTECT.
    SHARE        

    draws the legend in the procedure output area. If the legend is positioned over elements of the graph itself, both graphics elements and legend elements are displayed.

    By default, MODE=RESERVE unless POSITION=INSIDE. In this case, the default changes to MODE=PROTECT.