AXI4 Stream中position byte是什么意思？

xiangpeis

如题，在Stream中分为2种数据，一种是postion byte，一种是data byte，data byte容易理解，就是要传输的数据。可是position byte是什么呢？里面包含的是什么内容？用于做什么的？如果能举个小例子就更好了，请教高手解答，不胜感谢。

下面是摘自文档中的部分：
Data byte: A byte of data that contains valid information that is transmitted between the source and destination.
Position byte: A byte that indicates the relative positions of data bytes within the stream. This is a placeholder that does not contain any relevant data values that are transmitted between the source and destination.