Zeroth Row In a Table

Hi

I have come across a OLTP Database where all the tables has a default row as zeroth row, i am not sure why is it required in first place? can anyone explain what are the advantages and disadvantages of having zeroth row.

What do you mean by a zeroth row?

The disadvantage is bogus data and relationships. The only supposed advantage I can think of is avoiding NULL values in referencing FK columns, but the code still has to "know" to treat 0 as "no relationship" rather than NULL as "n r", so I don't see how it really helps.