MDS 9120 Zone broadcast attribute??

[DJCOOK]

Can somebody explain why i can remove the broadcast attribute from a zone via fabric manager, but it reappears.
I could probably remove it using cli but i wasn't quite sure if it was somehow needed for the default vsan??
See Config below

clear zone database vsan 1
config terminal
zone broadcast enable vsan 1
zone name fit1 vsan 1
member pwwn 50:08:05:f3:00:11:d5:81
member pwwn 50:08:05:f3:00:18:c4:c1
member pwwn 21:00:00:e0:8b:90:71:5e
zone name fit2 vsan 1
attribute broadcast
member pwwn 50:08:05:f3:00:11:d5:81
member pwwn 50:08:05:f3:00:18:c4:c1
member pwwn 10:00:00:00:c9:46:9d:81

Thanks,
DJCook