 parameter needs to be cast to a <b>void **pptr</b> as the API has currently the wrong signature; that will be changed in a future version. The <b>*pptr</b> is a pointer to the source exdata. When the dup_func() returns, the value in <b>*pptr</b> is copied to the destination ex_data. If the pointer contained in <b>*pptr</b> is not modified by the dup_func(), then both <b>to</b> and <b>from</b> will point to the same data. The <b>idx</b>, <b>argl</b> and <b>argp</b> parameters are as described for the other 