British Order: "Sustained Fire Training" Question

Hi,

I have a rules question and need clarification. The British and the ABDA Command Station have an advanced order called: "Sustained Fire Training" which means:

TIMING:Before rolling attack dice
+1 to the RoF of all guns in the squadron

What does it mean? Do I add 1 to the RoF to the sum of all weapon systems dice or do I add 1 to each single weapon system?
e.g.
a British Tribal Class destroyer has two rows of primary weapon systems with 4 ROF each. When shooting from broadside both systems can shoot with ROF 8 (4+4).
Does this order increase the ROF to 9 (8+1) or increase each row separately [(4+1)+(4+1)] = 10 ROF?

This is in the same line as the earlier question about what exactly is a weapon system. The bonus is for each weapon system, so the tribal class DD would get +2 RoF in the example. Ill revise the wording when I have the time (bit busy these weeks, its spring holiday here)

Thanks. Now everything is clear.

Regards,

Lindinho