Dynamic table in a table.

Hi Guys,

I would like to declare a row in a internal table as dynamic table, like this:

types: begin of typ_sentences,

         period         type bu_txt5000,

         ref              type data,

         nested_dynamic table TYPE ????,

        end of typ_sentences.

data: table type table of typ_sentences,

        wa like line of table.

call method cl_alv_table_create=>create_dynamic_table

         exporting

           it_fieldcatalog = tab_fieldcat

         importing

           ep_table        = wa-ref.

assign wa-ref->* to wa<nested_dynamic_table>.

wa-period = 2014.

append wa to table.

Or maybe something like this:

field-symbols: <main_struture> type ANY TABLE,

                     <nested_table> like table of <main_structure>.

Any suggestion?

Thanks in advanced.