5.10.4 from-page-master-region discrepancy?

In XSL-FO 1.1, 5.10.4, appears:

"If this function is used in an expression on a formatting object, F, that
is a descendant of an fo:page-sequence, then the computed value is taken
from the region specification that was used to generate the nearest
ancestor region reference area which has as its descendants the areas
returned by F."

However, this is followed by an example where "this function"
(from-page-master-region) is used on fo:page-sequence, and not a descendant
of fo:page-sequence!

<fo:page-sequence master-name="default-sequence"
                  writing-mode="from-page-master-region()">


How is this example to be reconciled with the normative language cited
above about being "used in an expression ... that is a descendant of an
fo:page-sequence"?

Regards,
Glenn