broader and broaderMatch

Hi!

Something I do not understand: why broaderMatch is a sub-property of 
broader and not the contrary?

For me:
<A> broader <B> means "A broader than B"
and
<A> broadMatch <B> means "A is used/is considered in practice/is mapped 
as being broader than B"

For me:
<A> broader <B> implies <A> broadMatch <B>
but not <A> broadMatch <B> implies <A> broader <B>

You can branch me to some document or tutorial (supplement to specs 
chapter 10.6) as this is a rather basic question!!!
This question is not "academic" as it is related with practical 
development issues.

Thanks!

Christophe