Stylesheet parameters and packages?

Dear xsl-list,

Is there a rule of thumb for managing stylesheet parameters when using a
package hierarchy, that is, in situations where packages use other
packages? I would like to set a $debug parameter in all packages, both the
lowest-level collections of user-defined functions and the higher-level
packages that import those libraries, and that are then imported,
themselves, by other stylesheets. But as I fiddle with the options, either
I am notified by the mid-level package that a parameter has not been
declared there (even though it is declared in a lower-level package that I
am using in the mid-level one, and the XSLT 3.0 spec tells me that
stylesheet parameters are obligatorily public) or, when I declare the
parameter in the mid-level package, that it conflicts with the lower-level
declaration. In case this is helpful, the point of the $debug parameter is
that I want to write diagnostic messages to stderr using <xsl:message>
 when the $debug parameter value is true, and I need to be able to generate
messages of this sort from both the low-level and mid-level packages.

Sincerely,

David
djbpitt@xxxxxxxxx