A parentless element that is not the document node - how?

Hi Folks,

The XSLT 2.0 spec talks about "parentless elements".  As far as I know,
there can only be one element in a source document that is parentless -
the document node.  Yet, the XSLT 2.0 spec seems to suggest that there
may be other parentless element nodes.  Can someone tell me what they
may be?  /Roger