SQL*Loader-00431
illegal NULLIF or DEFAULTIF clause specified for nested table column string
Cause
Rows in a nested table cannot be set to NULL. SQLLDR displays this error when a NULLIF clause was specified for the element that defines the row that make up a nested table. SQLLDR also displays this error if a DEFAULTIF clause is specified for an element that is a named type, since SQLLDR will set a named type to NULL if the DEFAULTIF evaluates to TRUE.