江湖救急！关于存储过程参数类型的问题！！！

存储过程的输入参数长度大于varchar2的4000时，该如何定义参数类型？我试了char和long都不行，都是报
Error -1460: ORA-01460: 转换请求无法实现或不合理
存储过程如下：type myrctype is ref cursor; procedure item_1a_gatherFQGeneral (itemids in char,rc out myrctype) 
is 
begin
open rc for 
select '' as itemid,'' as budgetid,'合计' as itemname,sum(b.nextyearinfinance) as nextyearinfinance,
sum(b.nextyearinfinanceoften) as nextyearinfinanceoften, sum(b.nextyearinfinancespecial) as nextyearinfinancespecial,
sum(b.nextyearinfinancefund) as nextyearinfinancefund, sum(b.nextyearinfinancecase) as nextyearinfinancecase,
sum(b.nextyearinfinancebuild) as nextyearinfinancebuild, sum(b.nextyearinfinancesuper) as nextyearinfinancesuper,
sum(b.nextyearinfinancebg) as nextyearinfinancebg, sum(b.nextyearsuper) as nextyearsuper,
sum(b.nextyearincome) as nextyearincome,sum(b.nextyearoutfinance) as nextyearoutfinance, 
sum(b.nextyearsub) as nextyearsub, sum(b.nextyearfund) as nextyearfund, 
sum(b.nextyearloan) as nextyearloan,sum(b.nextyearsurplus) as nextyearsurplus, 
sum(b.nextyearother) as nextyearother, sum(b.nextyearbak) as nextyearbak 
from item_1a_general a ,item_1a_bankrollsource b
where a.itemid=b.itemid and instr(itemids,a.itemid)>0
union all 
select a.itemid,a.budgetid,a.itemname,b.nextyearinfinance,
b.nextyearinfinanceoften, b.nextyearinfinancespecial,
b.nextyearinfinancefund, b.nextyearinfinancecase,
b.nextyearinfinancebuild, b.nextyearinfinancesuper,
b.nextyearinfinancebg, b.nextyearsuper, b.nextyearincome,
b.nextyearoutfinance, b.nextyearsub, b.nextyearfund, b.nextyearloan,
b.nextyearsurplus, b.nextyearother, b.nextyearbak 
from item_1a_general a ,item_1a_bankrollsource b
where a.itemid=b.itemid and instr(itemids,a.itemid)>0;
end item_1a_gatherFQGeneral;