I originally fell in love with chronos because is used the ISO 8601 standard for scheduling.
Reading the recent communications on the google group, it seems that chronos has fallen out of favor and that metronome is the new and redesigned native sheduling system.
While metronome supports cron notation for specifying scheduling, I personally feel that ISO 8601 is worth supporting.
API and UI support would be great
I was hoping to ask that this feature be included in a future release
I am not sure how difficult this would be and would be curious as to what developers would think.