alv中编辑的时候quan字段小数位数被截取掉

alv中编辑的时候quan字段小数位数被截取掉：位数太多(最大只能为 0)

解决方法：

ls_fcat-fieldname  =  'ZKBSL'.
  ls_fcat-coltext  =  '卡板数量'.
  ls_fcat-decimals = 3.
  ls_fcat-edit = 'X'.
  APPEND ls_fcat TO gt_fcat.
  CLEAR ls_fcat.