<s>
Apache	B-Language
POI	I-Language
,	O
a	O
project	O
run	O
by	O
the	O
Apache	O
Software	O
Foundation	O
,	O
and	O
previously	O
a	O
sub-project	O
of	O
the	O
Jakarta	B-Language
Project	I-Language
,	O
provides	O
pure	O
Java	B-Device
libraries	O
for	O
reading	O
and	O
writing	O
files	O
in	O
Microsoft	B-Application
Office	I-Application
formats	O
,	O
such	O
as	O
Word	B-Application
,	O
PowerPoint	B-Application
and	O
Excel	B-Application
.	O
</s>
<s>
The	O
name	O
was	O
originally	O
an	O
acronym	O
for	O
"	O
Poor	B-Language
Obfuscation	I-Language
Implementation	I-Language
"	O
,	O
referring	O
humorously	O
to	O
the	O
fact	O
that	O
the	O
file	O
formats	O
seemed	O
to	O
be	O
deliberately	O
obfuscated	O
,	O
but	O
poorly	O
,	O
since	O
they	O
were	O
successfully	O
reverse-engineered	O
.	O
</s>
<s>
POI	O
supports	O
the	O
ISO/IEC	B-Operating_System
29500:2008	I-Operating_System
Office	B-Operating_System
Open	I-Operating_System
XML	I-Operating_System
file	O
formats	O
since	O
version	O
3.5	O
.	O
</s>
<s>
A	O
significant	O
contribution	O
for	O
OOXML	B-Operating_System
support	O
came	O
from	O
Sourcesense	O
,	O
an	O
open	B-Application
source	I-Application
company	O
which	O
was	O
commissioned	O
by	O
Microsoft	O
to	O
develop	O
this	O
contribution	O
.	O
</s>
<s>
This	O
link	O
spurred	O
controversy	O
,	O
some	O
POI	O
contributors	O
questioning	O
POI	O
OOXML	B-Operating_System
patent	O
protection	O
regarding	O
Microsoft	O
's	O
Open	O
Specification	O
Promise	O
patent	O
license	O
.	O
</s>
<s>
The	O
Apache	B-Language
POI	I-Language
project	O
contains	O
the	O
following	O
subcomponents	O
(	O
meaning	O
of	O
acronyms	O
is	O
taken	O
from	O
old	O
documentation	O
)	O
:	O
</s>
<s>
POIFS	O
(	O
Poor	B-Language
Obfuscation	I-Language
Implementation	I-Language
File	O
System	O
)	O
–	O
This	O
component	O
reads	O
and	O
writes	O
Microsoft	O
's	O
OLE	O
2	O
Compound	B-Library
document	I-Library
format	O
.	O
</s>
<s>
Since	O
all	O
Microsoft	B-Application
Office	I-Application
files	O
are	O
OLE	O
2	O
files	O
,	O
this	O
component	O
is	O
the	O
basic	O
building	O
block	O
of	O
all	O
the	O
other	O
POI	O
elements	O
.	O
</s>
<s>
HSSF	B-Language
(	O
Horrible	O
SpreadSheet	O
Format	O
)	O
–	O
reads	O
and	O
writes	O
Microsoft	B-Application
Excel	I-Application
(	O
XLS	O
)	O
format	O
files	O
.	O
</s>
<s>
It	O
can	O
read	O
files	O
written	O
by	O
Excel	B-Application
97	O
onwards	O
;	O
this	O
file	O
format	O
is	O
known	O
as	O
the	O
BIFF	O
8	O
format	O
.	O
</s>
<s>
As	O
the	O
Excel	B-Application
file	O
format	O
is	O
complex	O
and	O
contains	O
a	O
number	O
of	O
tricky	O
characteristics	O
,	O
some	O
of	O
the	O
more	O
advanced	O
features	O
cannot	O
be	O
read	O
.	O
</s>
<s>
XSSF	O
(	O
XML	O
SpreadSheet	O
Format	O
)	O
–	O
reads	O
and	O
writes	O
Office	B-Operating_System
Open	I-Operating_System
XML	I-Operating_System
(	O
XLSX	B-Operating_System
)	O
format	O
files	O
.	O
</s>
<s>
Similar	O
feature	O
set	O
to	O
HSSF	B-Language
,	O
but	O
for	O
Office	B-Operating_System
Open	I-Operating_System
XML	I-Operating_System
files	O
.	O
</s>
<s>
HPSF	O
(	O
Horrible	O
Property	O
Set	O
Format	O
)	O
–	O
reads	O
"	O
Document	O
Summary	O
"	O
information	O
from	O
Microsoft	B-Application
Office	I-Application
files	O
.	O
</s>
<s>
This	O
is	O
essentially	O
the	O
information	O
that	O
one	O
can	O
see	O
by	O
using	O
the	O
File|Properties	O
menu	O
item	O
within	O
an	O
Office	B-Application
application	O
.	O
</s>
<s>
HWPF	O
(	O
Horrible	O
Word	B-Application
Processor	O
Format	O
)	O
–	O
aims	O
to	O
read	O
and	O
write	O
Microsoft	B-Application
Word	I-Application
97	I-Application
(	O
DOC	O
)	O
format	O
files	O
.	O
</s>
<s>
XWPF	O
(	O
XML	O
Word	B-Application
Processor	O
Format	O
)	O
–	O
similar	O
feature	O
set	O
to	O
HWPF	O
,	O
but	O
for	O
Office	B-Operating_System
Open	I-Operating_System
XML	I-Operating_System
files	O
.	O
</s>
<s>
HSLF	O
(	O
Horrible	O
Slide	O
Layout	O
Format	O
)	O
–	O
a	O
pure	O
Java	B-Device
implementation	O
for	O
Microsoft	B-Application
PowerPoint	I-Application
files	O
.	O
</s>
<s>
HDGF	O
(	O
Horrible	O
DiaGram	O
Format	O
)	O
–	O
an	O
initial	O
pure	O
Java	B-Device
implementation	O
for	O
Microsoft	B-Application
Visio	I-Application
binary	O
files	O
.	O
</s>
<s>
HPBF	O
(	O
Horrible	O
PuBlisher	O
Format	O
)	O
–	O
a	O
pure	O
Java	B-Device
implementation	O
for	O
Microsoft	O
Publisher	O
files	O
.	O
</s>
<s>
HSMF	O
(	O
Horrible	O
Stupid	O
Mail	O
Format	O
)	O
–	O
a	O
pure	O
Java	B-Device
implementation	O
for	O
Microsoft	O
Outlook	O
MSG	O
files	O
.	O
</s>
<s>
DDF	O
(	O
Dreadful	O
Drawing	O
Format	O
)	O
–	O
a	O
package	O
for	O
decoding	O
the	O
Microsoft	B-Application
Office	I-Application
Drawing	O
format	O
.	O
</s>
<s>
The	O
HSSF	B-Language
component	O
is	O
the	O
most	O
advanced	O
feature	O
of	O
the	O
library	O
.	O
</s>
<s>
The	O
POI	O
library	O
is	O
also	O
provided	O
as	O
a	O
Ruby	B-Language
or	O
ColdFusion	B-Language
extension	O
.	O
</s>
<s>
Apache	O
Hive/Apache	O
Flink/Apache	O
Spark	O
)	O
,	O
which	O
provide	O
certain	O
functionality	O
of	O
Apache	B-Language
POI	I-Language
,	O
such	O
as	O
the	O
processing	O
of	O
Excel	B-Application
files	O
.	O
</s>
