mylist1='"a1","a2 ",...,"a12"'
mylist2='"b1","b2 ",...,"b14"'

It works: select * from mytable WHERE INLIST(field1,&mylist1 ) '
It works: select * from mytable WHERE INLIST(field2,&mylist2 ) '
It does not work:
select * from mytable WHERE (INLIST(field1,&mylist1 ) or INLIST(field2,&mylist2 ))

However it works when the arquments in mylist1 and mylist2 are less than 6.
It is supposed that the arquments in the INLIST command can be up to 24

Thanks,
Yiorgos