Cron Expression

[Murali Narayanaswamy]

Hi All,
I want to build a cron expression for a job which occurs the last Wednesday of every 7 months. I built a cron expression as below

0 * * ? 0/7 4L

But the month field only takes values from 1 ~ 12. Pls let me know how to build an expression if there is monthly recurrences

Thanks much
Murali