On page 360 of the DW Rulebook, in the example of the Hordes' attack it states that:

"Any additional hits from sustained fire can be applied to any eligible target."

I can not find any description of this anywhere. I have a theory that it is in reference to a full auto shot or similar shot getting additional hits based on the degrees of success, but I am not sure. Any help on this would be greatly appreciated!

Thanks!

It's short hand for Semi- or Full Auto fire. It means, if a Mag 40 horde of Fire Warriors makes a Full Auto attack and rolls at least 3 DoS, the 4 hits from their Full Auto fire are not restricted to targets witin 2m of the initial target and can be applied to any target in range. It represents the fact that a Horde is not one shooter walking their fire between targets, but is a mass of individuals firing at multiple targets.

Gotcha! Thanks a lot for the fast response too!