sparse Key word use in sqlserver

declare  @sparsedtable table
(

c1 int primary key,
c2 int null,
c3 int default 0,
c4 int sparse,
c5 int sparse,
c6 int sparse,
cs xml column_set for all_sparse_columns)

insert into @sparsedtable(c1,c2,c3,c4,c5,c6)values(1,2,3,4,5,6)


declare  @sparsedtable1 table
(

c1 int primary key,
c2 int null,
c3 int default 0,
c4 int sparse,
c5 int sparse,
c6 int sparse,
c7 varchar(100) sparse,
cs varchar(max) sparse)

insert into @sparsedtable1(c1,c2,c3,c4,c5,c6,c7)values(1,2,3,4,5,6,'fds')

select * from @sparsedtable1

go

declare  @DocumentStore TABLE
    (DocID int PRIMARY KEY,
     Title varchar(200) NOT NULL,
     ProductionSpecification varchar(20) SPARSE NULL,
     ProductionLocation smallint SPARSE NULL,
     MarketingSurveyGroup varchar(20) SPARSE NULL,
     Mdate datetime SPARSE NULL,
     SpecialPurposeColumns XML COLUMN_SET FOR ALL_SPARSE_COLUMNS )


INSERT @DocumentStore(DocID, Title, ProductionSpecification, ProductionLocation,Mdate)
VALUES (1, 'Tire Spec 1', 'AXZZ217', 27,null)


INSERT @DocumentStore(DocID, Title, MarketingSurveyGroup,Mdate)
VALUES (2, 'Survey 2142', 'Men 25 - 35',null)


INSERT @DocumentStore(DocID, Title, MarketingSurveyGroup,Mdate)
VALUES (3, 'Survey 2142', getdate(), getdate())

INSERT @DocumentStore(DocID, Title, MarketingSurveyGroup,Mdate)
VALUES (4, getdate(), getdate(),null)
select * from @DocumentStore


Ref:http://msdn.microsoft.com/en-us/library/cc280604.aspx