<P>Several (co)inductive and (co)datatype definitions are presented. <A HREF="http://www.cl.cam.ac.uk/Research/Reports/TR312-lcp-set-II.ps.gz">One report</A> describes the theoretical foundations of datatypes while <A HREF="http://www.cl.cam.ac.uk/Research/Reports/TR320-lcp-isabelle-ind-defs.dvi.gz">another</A> describes the package that automates their declaration.