Technical Query: Population Logic for PAY_ACTION_INFORMATION (action_information 61 vs 81)

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Hi,

I am currently working with the pay_action_information table to extract regular salary amounts for specific pay periods. While my current query is functional, I have encountered some inconsistency in how the data is being stored.
The Issue:
In our environment, the salary data appears to shift between columns depending on the pay period:
In some periods, the data is populated in action_information61.
In other periods, the data is found in action_information81.
Our Goal:
We need to understand the exact logic or process that determines which of these columns is used. Relying on a query that checks both without knowing the "why" poses a risk for our long-term reporting accuracy.