EJB QL WHERE IN expression with parameter

Question

I would like to use an input parameter (?1) to represent an entire set ('A','B') inside the expression of the WHERE ... IN clause as follows:
SELECT OBJECT(t) FROM Table t WHERE t.field IN ('A','B')
SELECT OBJECT(t) FROM Table t WHERE t.field IN (?1)
Adding <ql-2.1-compatible/> into persistent.xml allows the last EJB-QL expression to be deployed.
Unfortunately, the parameter (?1) can only represent 1 member in the set.  Is there anywhere to get a single parameter (?1) to represent an entire set ('A','B','C','D') ?
Alton

Answer 1

michaels>  var par varchar2(100)
michaels>  exec :par := '7839,7698,7782'
PL/SQL procedure successfully completed.
michaels>  select *
  from emp
where empno in (
          select t.column_value.extract ('/r/text()').getnumberval() from table (xmlsequence (xmltype ('<r><r>' || replace (:par, ',', '</r><r>') || '</r></r>').extract ('//r'))) t)
     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
      7839 KING       PRESIDENT            17-NOV-81       5000                    10
      7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
      7698 BLAKE      MANAGER         7839 01-MAI-81       2850                    30