Hello Kiryl ,
Graphical mapping should do.
1.(number of ITEM) = (number of SPLIT) X (number of LINEITEM)
EMAIL = SPLIT[Owner]
Select statistic function count and arithmetic function multiply. You can use removecontexts if the splits are coming in different contexts.
ITem = Count[SPLIT} Multiply Count[LINEITEM]
2.EMAIL = SPLIT[Owner]
you can do a direct mapping here.
3.PARTN_ROLE = Index of SPLIT
Try index of function in TEXT. When you say index of split any character index in split?
4.ITM_NUMBER = LINEITEM[LineNumber]
you can do a direct mapping here.