Simple XSL Pipelines

Good day,

There are many ways to pipe XML output from one XSLT to another, but
what is the proper way to do it? Using a programming language in
between does the job, but is there some way to implement it elegantly
with XSLT and Saxon alone?

The idea is something like:
data.xml -> filter.xls -> layout.xls -> targetmedia.xsl ->
data_for_mobile_phone.svg

This is just a thumb [expletive deleted] example, but that's the idea.

I was thinking along the line of creating a master XSL such as
pipeline.xsl which would work on parameters and call the other style
sheets as required. I know I can do this easily from java, but I'm
looking for a pure XSL solution. Also, I need to to be able in use
more than one XML as input, which I know is not ideal, but it is
better to get the requirements right, and to make the technology fit,
than to get the technology right and to get the requirements to fit.

The answer probably lies in correct use of <xsl:variable
select="document(filter.xls)" name="filter" />, but I can't find an
elegant solution. If someone can help or make suggestions or give an
example that would be great.

Kind regards
Jacobus