If it has a sukun , then it is heavy if the first preceding letter without a sukun has a fatḥah or ḍammah and light when the first preceding letter without a sukun has a kasrah .
If it has a sukun , then it is heavy if the first preceding letter without a sukun has a fatḥah or ḍammah . 
 It is light when the first preceding letter without a sukun has a kasrah .