Reference Mode describes the relations between the table and the table that it is reference to in Reference table column.
There are below options available for Reference Mode
The table field must contain a value that is present in the reference table. For Example Currencies in say Supplier Master, the currency field in supplier master should mandatorily contain any one value which are present in the Currency Master table
Mandatory Unless Empty –
The table field can be empty.If the table field is filled,the field’s value must be present in the reference table. For example,the reference from Currency field in Supplier Master to Currency Master is mandatory unless empty.As a result,the Currency field in Supplier Master is optional i.e. it can contain null value.
Not Mandatory –
The table field can contain a value that is present in the reference table,but the table field can also contain another value.