10/2015 Update:  This is not currently supported in the CRON scheduler.  Will update this article when a suitable workaround is released.

Setting a specific ordinal of days (i.e the 3rd Saturday of the month) is not part of the cron scheduling mechanism which is used in the K1000.  But there are some clever things that may work.

Since you can set a schedule to only be active between certain days, and the 3rd Saturday would only ever fall between the 15th and the 21st of the month, we can setup a schedule that only patches on Saturdays between the 15th and the 21st.  

So a schedule to do this might be coded like this:

30 2 15-21 * 6

Translation:  2:30 am between the 15th and 21st ONLY on Saturdays of every month.

The cron custom schedule options are listed here....

*    *    *    *    *
-    -    -    -    -
|    |    |    |    |
|    |    |    |    +--------- day of week (0 - 6) (Sunday=0)
|    |    |    +---------- month (1 - 12)
|    |    +----------- day of month (1 - 31)
|    +------------ hour (0 - 23)
+------------- min (0 - 59)