Problems with nested lists

I am continuing to have problems with nested lists:
specifically, that the numbering notation seems to
be somewhat random in its selection of different
notation at different points in the list.  

Attached is a source XML file, the XSL used to transform
it (just a wrapper for the DocBook xsl - you will need to 
modify it to point to your own location) and the HTML 
that is generated.

I have been using Michael Kay's "Instant Saxon" on a
Windows XP machine.

Any help appreciated...

Derek

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