DECLARE
resultXML clob;
act1 varchar2( 1000 );
act2 varchar2( 1000 );
filter varchar2( 4000 );
BEGIN
act1 := wwv_flow.g_x01;/*Тип запроса*/
act2 := wwv_flow.g_x02;/*Тип БД*/
filter := wwv_flow.g_x03;/*Переменная фильтров*/

owa_util.mime_header('text/xml', FALSE );
HTP.print('Cache-Control: no-cache');
HTP.print('Pragma: no-cache');
owa_util.http_header_close;

HTP.print('<root><OPT>');
HTP.print('<act1>' || act1 || '</act1>');
HTP.print('<act2>' || act2 || '</act2>');
HTP.print('<act3>' || filter || '</act3>');
HTP.print('</OPT>');
resultXML:='';

if (act1='SELECT_DISTRICT')then
    resultXML:=geo.show_districts();
ELSIF (act1='SELECT_REGION') then
    resultXML:=geo.show_cities(filter);
ELSIF (act1='SELECT_CITY') then
    resultXML:=geo.show_cities(null,filter);
end if;

HTP.print(resultXML);
HTP.print('<RESULT>OK</RESULT>');
HTP.print('</root>');

END;

ORA- 06502 : PL/SQL: numeric or value error

HTP.print(resultXML);