Audit History Flow

I want to know the flow of Audit History for every page
1. How the histories are maintained for every Page?
2. What is the database flow for the tables used?
 

Below is the query I have created according to my understanding for the Sales Order Screen (SO301000). Is it correct to check the history for every OrderNbr.

Select 
Distinct u.username,
sl.OrderNbr,
au.ScreenID,
au.UserID,
au.ChangeDate,
sl.LastModifiedDateTime,
au.ChangeID,
au.BatchID,
au.Tablename,
au.ModifiedFields
From
SOLineSplit sl
Inner Join
AuditHistory au
ON sl.LastModifiedByID = au.USerID
Inner Join Users u
ON au.UserID = u.PKID
WHERE sl.OrderNbr = `ordernbr`and au.ScreenID = 'SO301000' and sl.LastModifiedByID = `userid`