Questions on Initializing Parameters for XSL

HI guys,

I've got a question on XSL parameter setting. There are two ways to init the
value of a parameter; one is to use transformer.setParameter(), another is
to use <xsl:parameter ...select="" />. My question is: which one is
overridden another? my understanding is the transformer one gonna override
the xsl one. Is it true?

Thanks,

Richard Qing