The option tcoNullable is used in SQL table columns to indicate that values in those columns can be NULL. However, this property is should be modeled in the type of the column.
As the type of an SQL table column already is capable of indicating whether NULL values are allowed the tcoNullable option for an SQL table column is deprecated. We should remove all references to tcoNullable and ensure that the types of the table columns that currently use the option are in fact nullable.