The null indicator is not relevant for the initial data
migration.
Your IRD decides if a nullable column value is valid or should
become null. When you want to specify a null value, move a predefined
character, such as ‘@' to the first value of the field in the
VIDLOAD output record. In your DB2® load
utility control cards, add the statement
NULLIF POS1:POS1 = '@'
to
the utility control cards.