rules for different classes

I'm using docbook-xsl-1.65.0/fo/docbook.xsl to
produce PDF via a saxon/fop workflow.

I don't want a header on the first page
a of chapter.  I've been able to stop text
being output to the header, but I'm unable
to suppress the header rule.  How can I
suppress the rule just on the first page
of a chapter?

In a similar question to the first: I only
want a footer on the first page of a chapter.
How can I suppress the footer rule on every page
except the first page of a chapter?