How to pass more than one value to the procedure

Question

How can I pass more than one letting date to this procedure. If it is only one letting date, I do not have a problem but when it is more than one letting date at the same time then I am stuck. please help
example I would like to pass this three letting dates : '01/17/2010', '01/27/2010','05/22/2010'
CEATE OR REPLACE PROCEDURE TPLCP.PLANHOLDERSLIST
P_LettingDate IN  VARCHAR2,
p_results OUT sys_refcursor
AS
BEGIN
    OPEN p_results FOR
SELECT DISTINCT DECODE (TRIM (MIN (j.route)), NULL, 'N/A',TRIM (MIN (j.route))) rt,l.lcontid conid,
                 SUBSTR (q.cprojnum, 1, 10) pr, SUBSTR (l.letting, 3, 2)|| '-'|| SUBSTR (l.letting, 5, 2)|| '-'|| SUBSTR (l.letting, 1, 2) lt,
                (q.cdescr) jbtyp, INITCAP (q.clocat1 || q.clocat2) loc
           FROM vendor v,
                vendaddr r,
                letprop l,
                planhold p,
                proposal q,
                project j,
                propproj k,
                bidlet bd
          WHERE v.vendor = r.vendor
            AND k.contid = q.contid
            AND k.pcn = j.pcn
            AND l.lcontid = k.contid
            AND p.vendor = v.vendor
            AND l.letting = p.letting
            AND TO_CHAR (bd.datelet, 'MM/DD/YYYY') IN P_LettingDate
            AND l.CALL = p.CALL
            AND r.addrnum = p.billto
            AND bd.letting = l.letting
       GROUP BY v.vendor,
                r.addrnum,
                v.vnamel,
                r.aaddr1,
                p.billto,
                r.acity,
                r.astate,
                q.cdescr,
                q.clocat1,
                q.clocat2,
                bd.letting,
                r.azipcode,
                r.vasst1,
                r.aphone,
                l.letting,
                l.lcontid,
                q.cprojnum;
END PLANHOLDERSLIST;

Answer 1

you can create your on array type and then pass that as the parameter. I use the suffix of ttyp to represent a table type.  The name of the column when using the table() syntax is columnvalue.
I altered my session to set the default date format to match your format. you could have used the to_date function to set the values for the arr type.
Hope this helps.
create type msw_ttyp as table of date
create or replace
procedure msw_test(p_arr     in msw_ttyp) as
v     integer;
begin
select count(*)
   into v
   from table(p_arr);
dbms_output.put_line('count: '||v);
for rec in (select column_value
               from table(p_arr))
loop
  dbms_output.put_line(rec.column_value);
end loop;
end msw_test;
alter session set nls_date_format = 'MM/DD/YYYY';
set serveroutput on size 1000000
exec msw_test(msw_ttyp('01/17/2010', '01/27/2010','05/22/2010'));
begin
msw_test(msw_ttyp(to_date('01/17/2010', 'MM/DD/YYYY'),
                   to_date('01/27/2010', 'MM/DD/YYYY'),
                   to_date('05/22/2010', 'MM/DD/YYYY')));
end;
/