BUILTIN.DF(transactionLine.createdfrom) AS so#
BreakDown of Code:
transactionLine.createdfrom
Refers to the Created From field at the line level of a transaction.
This field stores the internal ID of the source transaction (e.g., a Sales Order for an Invoice or an Item Receipt for a Purchase Order).
BUILTIN.DF(field)
BUILTIN.DF() is a NetSuite built-in function that retrieves the display value of a field instead of its internal ID.
In this case, it converts the createdfrom field (which normally stores an internal ID) into the corresponding transaction document number.
AS so#
Renames the extracted value as so# (short for “Sales Order Number” or similar) in the query results.