If an expression reference another expression in a parent fo, the parent fo expression must be evaluated against the LayoutContext that was in effect for the parent fo and *not* against the child fo LayoutContext.
<fo:block id="a" border-start-width="10%"> <fo:block id="b" border-start-width="inherit">
It must be the LayoutContex for 'a' that is used when we evaluate the 10% even when we call:
with the layout context for 'b'.
Well, I used to believe the 10% has been evaluated already, and the inherited property can grab the absolute value immediately.