Any Idea What The Purpose Of This SPROC Might Be? (no Prizes, Sorry!)

I've been asked to document an application and I'm going through all
the Stored Procedures and trying to work out what they're supposed to
do.

Can anyone give me an idea of what the Stored Procedure
wsBookingListsGetAll below is trying to achieve? Is it incomplete? I
can't see any reason to pass in the Parameter, and what is the UNION
SELECT 0 all about?

Many thanks

Edward


CREATE Procedure wsBookingListsGetAll
@DebtorIDvarchar(15)
As
set nocount on

SELECT
fldBookingListID
FROM
tblWsBookingList
UNION
SELECT 0


return

GO

/* Table def */
if exists (select * from dbo.sysobjects where id =
object_id(N'[dbo].[tblWSBookingList]') and OBJECTPROPERTY(id,
N'IsUserTable') = 1)
drop table [dbo].[tblWSBookingList]
GO

CREATE TABLE [dbo].[tblWSBookingList] (
[fldDebtorID] [char] (15) COLLATE Latin1_General_CI_AS NOT NULL ,
[fldBookingName] [varchar] (50) COLLATE Latin1_General_CI_AS NOT NULL
,
[fldAddressCode] [char] (15) COLLATE Latin1_General_CI_AS NOT NULL ,
[fldEmail] [varchar] (250) COLLATE Latin1_General_CI_AS NOT NULL ,
[fldFirstName] [varchar] (100) COLLATE Latin1_General_CI_AS NOT NULL ,
[fldLastName] [varchar] (100) COLLATE Latin1_General_CI_AS NOT NULL ,
[fldBookingListID] [int] IDENTITY (1, 1) NOT NULL ,
[fldInvoiceNumber] [varchar] (15) COLLATE Latin1_General_CI_AS NULL ,
[fldPayeeID] [char] (15) COLLATE Latin1_General_CI_AS NULL
) ON [PRIMARY]
GO