If procedure type is set to Sub device output then any output text generated by that procedure will be sent to the selected POD. The text may be static text on a map, or a local field previously filled with data, or a combination of static text and field data.
Output can also be sent to a POD if the procedure type is set to Print and a POD has been selected by a parent procedure. Obviously your program must be sure what PODs may have been previously selected when the procedure is activated.