特殊用法back porch1.后沿back-back porch1.水平同步信号后沿(时间), 后肩区(电视信号)back porch of pedestal1.(同步脉冲后面)熄灭脉冲后沿black porch1.黑肩front porch1.前沿front porch of pedestal1.同步脉冲前的消隐脉冲肩sun porch1.【建】玻璃圈起来的门廊