关于HEC-RAS的问题

第一个：
在定义“inline structure"时，其中有一个对话框是“inline weir station elavation editor"其中的第二项要输“width"手册是这样解释的“
Width - The width field is used to enter the width of the top of the
embankment along the stream. The distance between the top of the
embankment and the downstream bounding cross section will equal the main
channel reach length of the upstream cross section minus the sum of the
weir/embankment "width" and the "distance" between the embankment and
the upstream section. The width of the embankment should be entered in feet
(meters for metric).没弄明白是啥意思，可以帮忙解释一下吗？
第二个："inline structure"同"lateral structure"有什么区别？
请各位不惜赐教，我在这里先谢了！