What is meant by the the barrier (sutrah) that a worshipper takes, and is a prayer rug considered a barrier, making it permissible to pass at its end?

The sutrah for the worshiper is what he places in front of him to prevent people from passing and to enable him to achieve a state of humility (khushu'). Some scholars have considered a line drawn on the ground as a substitute for it when it is unavailable. Others hold that the end of the prayer rug serves the purpose of the line when a sutrah is absent or cannot be obtained.