Org Parameter Serial Generation Option "At Item level" Vs "At Organization level"?

Summary:

I am trying to understand the Organization Parameter Generation Option difference between "At Item level" Vs "At Organization level"?

Organization Parameter:

"At Organization level" means how Serail number gets generated

"At Item level" means , we have the flexibility to select Generation method at each item level (like Dynamic entry, Predefined etc)

But unable to understand if "At Organization level" how actually serails get generated, is it using Generate Serail number ESS job? that means only Predefined is the option we have if we have selected "At Organization level"?

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