doc_read_data_area
doc_read_data_area(docg3, &status, 1, 1);
doc_read_data_area(docg3, buf, 1, first);
doc_read_data_area(docg3, buf ? buf + 1 : buf, len - 1, 0);
doc_read_data_area(docg3, buf, len, first);