Can't figure out how INTERVAL and DELAY ON/OFF working together in PLEG schedule

Trying to configure a light when i’m out to go on and off (ghost scene), with a maximum on/off time and with a random on/off time.

Ex:

Every 30 mins, open the light for 15 to 30 mins. Which means the off time should be between 0 and 15 mins maximum.

Somebody could you tell me how to set it with PLEG.

Note the control is done with a virtual switch triggered by a scene days/night. The condition is ok too… but the interval and delay… I don’t fu… understand. ;-(

Do not double post … best way to get ignored …

See answer at:
http://forum.micasaverde.com/index.php/topic,31510.msg227686.html#msg227686

Sorry i should have post only once in the other thread.

Thanks a lot.