安全边际是预计销售量（销售额）保本销售量（销售额）差。
The margin of safety isi the excess of expected sales over breakeven sales .
关于多品种条件下保本分析中综合保本销售额计算公式的数学推导
A Mathematical Dedution on Break - even Point in Sales under Multiple Products
保本销售额保本销售额保本销售额