<s>
In	O
computing	O
,	O
a	O
legacy	B-Device
system	I-Device
is	O
an	O
old	O
method	O
,	O
technology	O
,	O
computer	O
system	O
,	O
or	O
application	B-Application
program	I-Application
,	O
"	O
of	O
,	O
relating	O
to	O
,	O
or	O
being	O
a	O
previous	O
or	O
outdated	O
computer	O
system	O
"	O
,	O
yet	O
still	O
in	O
use	O
.	O
</s>
<s>
Legacy	B-Device
code	I-Device
is	O
old	O
computer	O
source	O
code	O
that	O
is	O
no	O
longer	O
supported	O
on	O
the	O
standard	O
hardware	B-Architecture
and	O
environments	O
,	O
and	O
is	O
a	O
codebase	O
that	O
is	O
in	O
some	O
respect	O
obsolete	O
or	O
supporting	O
something	O
obsolete	O
.	O
</s>
<s>
Legacy	B-Device
code	I-Device
may	O
be	O
written	O
in	O
programming	O
languages	O
,	O
use	O
frameworks	B-Architecture
and	O
external	O
libraries	O
,	O
or	O
use	O
architecture	B-General_Concept
and	O
patterns	O
that	O
are	O
no	O
longer	O
considered	O
modern	O
,	O
increasing	O
the	O
mental	O
burden	O
and	O
ramp-up	O
time	O
for	O
software	B-General_Concept
engineers	I-General_Concept
who	O
work	O
on	O
the	O
codebase	O
.	O
</s>
<s>
Legacy	B-Device
code	I-Device
may	O
have	O
zero	O
or	O
insufficient	O
automated	B-Application
tests	I-Application
,	O
making	O
refactoring	O
dangerous	O
and	O
likely	O
to	O
introduce	O
bugs	B-Error_Name
.	O
</s>
<s>
Long-lived	O
code	O
is	O
susceptible	O
to	O
software	O
rot	O
,	O
where	O
changes	O
to	O
the	O
runtime	O
environment	O
,	O
or	O
surrounding	O
software	O
or	O
hardware	B-Architecture
may	O
require	O
maintenance	O
or	O
emulation	B-Application
of	O
some	O
kind	O
to	O
keep	O
working	O
.	O
</s>
<s>
Legacy	B-Device
code	I-Device
may	O
be	O
present	O
to	O
support	O
legacy	B-Device
hardware	I-Device
,	O
a	O
separate	O
legacy	B-Device
system	I-Device
,	O
or	O
a	O
legacy	O
customer	O
using	O
an	O
old	O
feature	O
or	O
software	O
version	O
.	O
</s>
<s>
While	O
the	O
term	O
usually	O
refers	O
to	O
source	O
code	O
,	O
it	O
can	O
also	O
apply	O
to	O
executable	B-Application
code	I-Application
that	O
no	O
longer	O
runs	O
on	O
a	O
later	O
version	O
of	O
a	O
system	O
,	O
or	O
requires	O
a	O
compatibility	B-General_Concept
layer	I-General_Concept
to	O
do	O
so	O
.	O
</s>
<s>
An	O
example	O
would	O
be	O
a	O
classic	O
Macintosh	B-Device
application	B-Application
which	O
will	O
not	O
run	O
natively	O
on	O
macOS	B-Application
,	O
but	O
runs	O
inside	O
the	O
Classic	O
environment	O
,	O
or	O
a	O
Win16	B-Library
application	B-Application
running	O
on	O
Windows	B-Application
XP	I-Application
using	O
the	O
Windows	B-Application
on	I-Application
Windows	I-Application
feature	O
in	O
XP	B-Application
.	O
</s>
<s>
An	O
example	O
of	O
legacy	B-Device
hardware	I-Device
are	O
legacy	B-Device
ports	I-Device
like	O
PS/2	O
and	O
VGA	O
ports	O
,	O
and	O
CPUs	O
with	O
older	O
,	O
incompatible	O
instruction	B-General_Concept
sets	I-General_Concept
(	O
with	O
e.g.	O
</s>
<s>
newer	O
operating	B-General_Concept
systems	I-General_Concept
)	O
.	O
</s>
<s>
Examples	O
in	O
legacy	B-Device
software	I-Device
include	O
legacy	B-Device
file	I-Device
formats	I-Device
like	O
.swf	O
for	O
Adobe	B-Operating_System
Flash	I-Operating_System
or	O
.123	O
for	O
Lotus	B-Application
1-2-3	I-Application
,	O
and	O
text	O
files	O
encoded	O
with	O
legacy	O
character	B-General_Concept
encodings	I-General_Concept
like	O
EBCDIC	B-Language
.	O
</s>
<s>
Legacy	O
was	O
often	O
heard	O
during	O
a	O
conversion	O
process	O
,	O
for	O
example	O
,	O
when	O
moving	O
data	O
from	O
the	O
legacy	B-Device
system	I-Device
to	O
a	O
new	O
database	O
.	O
</s>
<s>
While	O
this	O
term	O
may	O
indicate	O
that	O
some	O
engineers	O
may	O
feel	O
that	O
a	O
system	O
is	O
out	O
of	O
date	O
,	O
a	O
legacy	B-Device
system	I-Device
can	O
continue	O
to	O
be	O
used	O
for	O
a	O
variety	O
of	O
reasons	O
.	O
</s>
<s>
In	O
addition	O
,	O
the	O
decision	O
to	O
keep	O
an	O
old	O
system	O
may	O
be	O
influenced	O
by	O
economic	O
reasons	O
such	O
as	O
return	O
on	O
investment	O
challenges	O
or	O
vendor	O
lock-in	O
,	O
the	O
inherent	O
challenges	O
of	O
change	B-Application
management	I-Application
,	O
or	O
a	O
variety	O
of	O
other	O
reasons	O
other	O
than	O
functionality	O
.	O
</s>
<s>
Backward	B-General_Concept
compatibility	I-General_Concept
(	O
such	O
as	O
the	O
ability	O
of	O
newer	O
systems	O
to	O
handle	O
legacy	B-Device
file	I-Device
formats	I-Device
and	O
character	B-General_Concept
encodings	I-General_Concept
)	O
is	O
a	O
goal	O
that	O
software	B-Application
developers	I-Application
often	O
include	O
in	O
their	O
work	O
.	O
</s>
<s>
Even	O
if	O
it	O
is	O
no	O
longer	O
used	O
,	O
a	O
legacy	B-Device
system	I-Device
may	O
continue	O
to	O
impact	O
the	O
organization	O
due	O
to	O
its	O
historical	O
role	O
.	O
</s>
<s>
In	O
either	O
case	O
,	O
the	O
effect	O
on	O
business	B-General_Concept
intelligence	I-General_Concept
and	O
operational	B-General_Concept
reporting	I-General_Concept
can	O
be	O
significant	O
.	O
</s>
<s>
A	O
legacy	B-Device
system	I-Device
may	O
include	O
procedures	O
or	O
terminology	O
which	O
are	O
no	O
longer	O
relevant	O
in	O
the	O
current	O
context	O
,	O
and	O
may	O
hinder	O
or	O
confuse	O
understanding	O
of	O
the	O
methods	O
or	O
technologies	O
used	O
.	O
</s>
<s>
Organizations	O
can	O
have	O
compelling	O
reasons	O
for	O
keeping	O
a	O
legacy	B-Device
system	I-Device
,	O
such	O
as	O
:	O
</s>
<s>
The	O
costs	O
of	O
redesigning	O
or	O
replacing	O
the	O
system	O
are	O
prohibitive	O
because	O
it	O
is	O
large	O
,	O
monolithic	B-Architecture
,	O
and/or	O
complex	O
.	O
</s>
<s>
Examples	O
include	O
systems	O
to	O
handle	O
customers	O
 '	O
accounts	O
in	O
banks	O
,	O
computer	B-Application
reservations	I-Application
systems	I-Application
,	O
air	B-Application
traffic	I-Application
control	I-Application
,	O
energy	O
distribution	O
(	O
power	O
grids	O
)	O
,	O
nuclear	O
power	O
plants	O
,	O
military	O
defense	O
installations	O
,	O
and	O
systems	O
such	O
as	O
the	O
TOPS	B-Application
database	O
.	O
</s>
<s>
Legacy	B-Device
systems	I-Device
are	O
considered	O
to	O
be	O
potentially	O
problematic	O
by	O
some	O
software	B-General_Concept
engineers	I-General_Concept
for	O
several	O
reasons	O
.	O
</s>
<s>
If	O
legacy	B-Device
software	I-Device
runs	O
on	O
only	O
antiquated	O
hardware	B-Architecture
,	O
the	O
cost	O
of	O
maintaining	O
the	O
system	O
may	O
eventually	O
outweigh	O
the	O
cost	O
of	O
replacing	O
both	O
the	O
software	O
and	O
hardware	B-Architecture
unless	O
some	O
form	O
of	O
emulation	B-Application
or	O
backward	B-General_Concept
compatibility	I-General_Concept
allows	O
the	O
software	O
to	O
run	O
on	O
new	O
hardware	B-Architecture
.	O
</s>
<s>
Legacy	B-Device
systems	I-Device
may	O
have	O
vulnerabilities	O
in	O
older	O
operating	B-General_Concept
systems	I-General_Concept
or	O
applications	O
due	O
to	O
lack	O
of	O
security	O
patches	O
being	O
available	O
or	O
applied	O
.	O
</s>
<s>
These	O
issues	O
can	O
put	O
the	O
legacy	B-Device
system	I-Device
at	O
risk	O
of	O
being	O
compromised	O
by	O
attackers	O
or	O
knowledgeable	O
insiders	O
.	O
</s>
<s>
Some	O
of	O
this	O
"	O
glue	O
"	O
code	O
is	O
occasionally	O
developed	O
by	O
vendors	O
and	O
enthusiasts	O
of	O
particular	O
legacy	B-Device
technologies	I-Device
.	O
</s>
<s>
Budgetary	O
constraints	O
often	O
lead	O
corporations	O
to	O
not	O
address	O
the	O
need	O
of	O
replacement	O
or	O
migration	O
of	O
a	O
legacy	B-Device
system	I-Device
.	O
</s>
<s>
However	O
,	O
companies	O
often	O
do	O
n't	O
consider	O
the	O
increasing	O
supportability	O
costs	O
(	O
people	O
,	O
software	O
and	O
hardware	B-Architecture
,	O
all	O
mentioned	O
above	O
)	O
and	O
do	O
not	O
take	O
into	O
consideration	O
the	O
enormous	O
loss	O
of	O
capability	O
or	O
business	O
continuity	O
if	O
the	O
legacy	B-Device
system	I-Device
were	O
to	O
fail	O
.	O
</s>
<s>
Due	O
to	O
the	O
fact	O
that	O
most	O
legacy	B-Device
programmers	I-Device
are	O
entering	O
retirement	O
age	O
and	O
the	O
number	O
of	O
young	O
engineers	O
replacing	O
them	O
is	O
very	O
small	O
,	O
there	O
is	O
an	O
alarming	O
shortage	O
of	O
available	O
workforce	O
.	O
</s>
<s>
This	O
in	O
turn	O
results	O
in	O
difficulty	O
in	O
maintaining	O
legacy	B-Device
systems	I-Device
,	O
as	O
well	O
as	O
an	O
increase	O
in	O
costs	O
of	O
procuring	O
experienced	O
programmers	B-Application
.	O
</s>
<s>
Some	O
legacy	B-Device
systems	I-Device
have	O
a	O
hard	O
limit	O
on	O
their	O
total	O
capacity	O
which	O
may	O
not	O
be	O
enough	O
for	O
today	O
's	O
needs	O
,	O
for	O
example	O
the	O
4	O
GB	O
memory	O
limit	O
on	O
many	O
older	O
x86	B-Operating_System
CPUs	O
,	O
or	O
the	O
4	B-Protocol
billion	I-Protocol
address	I-Protocol
limit	I-Protocol
in	O
IPv4	B-Protocol
.	O
</s>
<s>
Where	O
it	O
is	O
impossible	O
to	O
replace	O
legacy	B-Device
systems	I-Device
through	O
the	O
practice	O
of	O
application	B-Application
retirement	I-Application
,	O
it	O
is	O
still	O
possible	O
to	O
enhance	O
(	O
or	O
"	O
re-face	O
"	O
)	O
them	O
.	O
</s>
<s>
Most	O
development	O
often	O
goes	O
into	O
adding	O
new	O
interfaces	O
to	O
a	O
legacy	B-Device
system	I-Device
.	O
</s>
<s>
The	O
most	O
prominent	O
technique	O
is	O
to	O
provide	O
a	O
Web-based	O
interface	O
to	O
a	O
terminal-based	O
mainframe	B-Architecture
application	B-Application
.	O
</s>
<s>
John	O
McCormick	O
discusses	O
such	O
strategies	O
that	O
involve	O
middleware	B-General_Concept
.	O
</s>
<s>
Printing	O
improvements	O
are	O
problematic	O
because	O
legacy	B-Device
software	I-Device
systems	O
often	O
add	O
no	O
formatting	O
instructions	O
,	O
or	O
they	O
use	O
protocols	O
that	O
are	O
not	O
usable	O
in	O
modern	O
PC/Windows	O
printers	O
.	O
</s>
<s>
Rich	O
Text	O
Format	O
(	O
RTF	O
)	O
or	O
PostScript	B-Language
documents	O
may	O
be	O
created	O
in	O
the	O
legacy	B-Device
application	I-Device
and	O
then	O
interpreted	O
at	O
a	O
PC	O
before	O
being	O
printed	O
.	O
</s>
<s>
Biometric	O
security	O
measures	O
are	O
difficult	O
to	O
implement	O
on	O
legacy	B-Device
systems	I-Device
.	O
</s>
<s>
A	O
workable	O
solution	O
is	O
to	O
use	O
a	O
Telnet	B-Protocol
or	O
HTTP	B-Protocol
proxy	B-Application
server	I-Application
to	O
sit	O
between	O
users	O
and	O
the	O
mainframe	B-Architecture
to	O
implement	O
secure	O
access	O
to	O
the	O
legacy	B-Device
application	I-Device
.	O
</s>
<s>
The	O
change	O
being	O
undertaken	O
in	O
some	O
organizations	O
is	O
to	O
switch	O
to	O
automated	B-Application
business	O
process	O
(	O
ABP	O
)	O
software	O
which	O
generates	O
complete	O
systems	O
.	O
</s>
<s>
These	O
systems	O
can	O
then	O
interface	O
to	O
the	O
organizations	O
 '	O
legacy	B-Device
systems	I-Device
and	O
use	O
them	O
as	O
data	B-Protocol
repositories	I-Protocol
.	O
</s>
<s>
This	O
approach	O
can	O
provide	O
a	O
number	O
of	O
significant	O
benefits	O
:	O
the	O
users	O
are	O
insulated	O
from	O
the	O
inefficiencies	O
of	O
their	O
legacy	B-Device
systems	I-Device
,	O
and	O
the	O
changes	O
can	O
be	O
incorporated	O
quickly	O
and	O
easily	O
in	O
the	O
ABP	O
software	O
.	O
</s>
<s>
Model-driven	B-Language
reverse	O
and	O
forward	O
engineering	O
approaches	O
can	O
be	O
also	O
used	O
for	O
the	O
improvement	O
of	O
legacy	B-Device
software	I-Device
.	O
</s>
<s>
Andreas	O
M	O
.	O
Hein	O
,	O
from	O
the	O
Technical	O
University	O
of	O
Munich	O
,	O
researched	O
the	O
use	O
of	O
legacy	B-Device
systems	I-Device
in	O
space	O
exploration	O
.	O
</s>
<s>
According	O
to	O
Hein	O
,	O
legacy	B-Device
systems	I-Device
are	O
attractive	O
for	O
reuse	O
if	O
an	O
organization	O
has	O
the	O
capabilities	O
for	O
verification	O
,	O
validation	O
,	O
testing	O
,	O
and	O
operational	O
history	O
.	O
</s>
<s>
The	O
original	O
hardware	B-Architecture
completed	O
the	O
expensive	O
integration	O
and	O
certification	O
requirement	O
for	O
flight	O
,	O
but	O
any	O
new	O
equipment	O
would	O
have	O
had	O
to	O
go	O
through	O
that	O
entire	O
process	O
again	O
.	O
</s>
<s>
Thus	O
any	O
new	O
system	O
that	O
started	O
the	O
certification	O
process	O
becomes	O
a	O
de	O
facto	O
legacy	B-Device
system	I-Device
by	O
the	O
time	O
it	O
is	O
approved	O
for	O
flight	O
.	O
</s>
<s>
Some	O
in	O
the	O
software	B-General_Concept
engineering	I-General_Concept
prefer	O
to	O
describe	O
"	O
legacy	B-Device
code	I-Device
"	O
without	O
the	O
connotation	O
of	O
being	O
obsolete	O
.	O
</s>
<s>
Eli	O
Lopian	O
,	O
CEO	O
of	O
Typemock	O
,	O
has	O
defined	O
it	O
as	O
"	O
code	O
that	O
developers	B-Application
are	O
afraid	O
to	O
change	O
"	O
.	O
</s>
<s>
Michael	O
Feathers	O
introduced	O
a	O
definition	O
of	O
legacy	B-Device
code	I-Device
as	O
code	O
without	O
tests	O
,	O
which	O
reflects	O
the	O
perspective	O
of	O
legacy	B-Device
code	I-Device
being	O
difficult	O
to	O
work	O
with	O
in	O
part	O
due	O
to	O
a	O
lack	O
of	O
automated	B-Application
regression	O
tests	O
.	O
</s>
<s>
He	O
also	O
defined	O
characterization	B-General_Concept
tests	I-General_Concept
to	O
start	O
putting	O
legacy	B-Device
code	I-Device
under	O
test	O
.	O
</s>
<s>
Ginny	O
Hendry	O
characterized	O
creation	O
of	O
code	O
as	O
a	O
`challenge`	O
to	O
current	O
coders	B-Application
to	O
create	O
code	O
that	O
is	O
"	O
like	O
other	O
legacies	O
in	O
our	O
lives	O
—	O
like	O
the	O
antiques	O
,	O
heirlooms	O
,	O
and	O
stories	O
that	O
are	O
cherished	O
and	O
lovingly	O
passed	O
down	O
from	O
one	O
generation	O
to	O
the	O
next	O
.	O
</s>
<s>
What	O
if	O
legacy	B-Device
code	I-Device
was	O
something	O
we	O
took	O
pride	O
in	O
?	O
</s>
<s>
The	O
term	O
legacy	B-Device
support	I-Device
is	O
often	O
used	O
in	O
conjunction	O
with	O
legacy	B-Device
systems	I-Device
.	O
</s>
<s>
For	O
example	O
,	O
Operating	B-General_Concept
systems	I-General_Concept
with	O
"	O
legacy	B-Device
support	I-Device
"	O
can	O
detect	O
and	O
use	O
older	O
hardware	B-Architecture
.	O
</s>
<s>
a	O
software	O
or	O
hardware	B-Architecture
vendor	O
that	O
is	O
supporting	O
,	O
or	O
providing	O
software	O
maintenance	O
,	O
for	O
older	O
products	O
.	O
</s>
<s>
A	O
legacy	B-Device
product	I-Device
may	O
have	O
some	O
advantage	O
over	O
a	O
modern	O
product	O
making	O
it	O
appealing	O
for	O
customers	O
to	O
keep	O
it	O
around	O
.	O
</s>
<s>
The	O
term	O
"	O
legacy	O
mode	O
"	O
often	O
refers	O
specifically	O
to	O
backward	B-General_Concept
compatibility	I-General_Concept
.	O
</s>
<s>
This	O
kind	O
of	O
feature	O
is	O
common	O
in	O
operating	B-General_Concept
systems	I-General_Concept
and	O
internet	O
browsers	O
,	O
where	O
many	O
applications	O
depend	O
on	O
these	O
underlying	O
components	O
.	O
</s>
<s>
The	O
computer	B-Architecture
mainframe	I-Architecture
era	O
saw	O
many	O
applications	O
running	O
in	O
legacy	O
mode	O
.	O
</s>
<s>
In	O
the	O
modern	O
business	O
computing	O
environment	O
,	O
n-tier	B-Operating_System
,	O
or	O
3-tier	B-Operating_System
architectures	I-Operating_System
are	O
more	O
difficult	O
to	O
place	O
into	O
legacy	O
mode	O
as	O
they	O
include	O
many	O
components	O
making	O
up	O
a	O
single	O
system	O
.	O
</s>
<s>
Virtualization	B-Architecture
technology	O
is	O
a	O
recent	O
innovation	O
allowing	O
legacy	B-Device
systems	I-Device
to	O
continue	O
to	O
operate	O
on	O
modern	O
hardware	B-Architecture
by	O
running	O
older	O
operating	B-General_Concept
systems	I-General_Concept
and	O
browsers	O
on	O
a	O
software	O
system	O
that	O
emulates	B-Application
legacy	B-Device
hardware	I-Device
.	O
</s>
<s>
Programmers	B-Application
have	O
borrowed	O
the	O
term	O
brownfield	O
from	O
the	O
construction	O
industry	O
,	O
where	O
previously	O
developed	O
land	O
(	O
often	O
polluted	O
and	O
abandoned	O
)	O
is	O
described	O
as	O
brownfield	O
.	O
</s>
<s>
Brownfield	O
architecture	B-General_Concept
is	O
a	O
type	O
of	O
software	O
or	O
network	O
architecture	B-General_Concept
that	O
incorporates	O
legacy	B-Device
systems	I-Device
.	O
</s>
<s>
Brownfield	O
deployment	O
is	O
an	O
upgrade	O
or	O
addition	O
to	O
an	O
existing	O
software	O
or	O
network	O
architecture	B-General_Concept
that	O
retains	O
legacy	O
components	O
.	O
</s>
<s>
There	O
is	O
an	O
alternate	O
favorable	O
opinion	O
—	O
growing	O
since	O
the	O
end	O
of	O
the	O
Dotcom	O
bubble	O
in	O
1999	O
—	O
that	O
legacy	B-Device
systems	I-Device
are	O
simply	O
computer	O
systems	O
in	O
working	O
use	O
:	O
</s>
<s>
IT	O
analysts	O
estimate	O
that	O
the	O
cost	O
of	O
replacing	O
business	B-Architecture
logic	I-Architecture
is	O
about	O
five	O
times	O
that	O
of	O
reuse	O
,	O
even	O
discounting	O
the	O
risk	O
of	O
system	O
failures	O
and	O
security	O
breaches	O
.	O
</s>
<s>
Ideally	O
,	O
businesses	O
would	O
never	O
have	O
to	O
rewrite	O
most	O
core	O
business	B-Architecture
logic	I-Architecture
:	O
debits	O
=	O
credits	O
is	O
a	O
perennial	O
requirement	O
.	O
</s>
<s>
The	O
IT	O
industry	O
is	O
responding	O
with	O
"	O
legacy	O
modernization	O
"	O
and	O
"	O
legacy	O
transformation	O
"	O
:	O
refurbishing	O
existing	O
business	B-Architecture
logic	I-Architecture
with	O
new	O
user	O
interfaces	O
,	O
sometimes	O
using	O
screen	O
scraping	O
and	O
service-enabled	O
access	O
through	O
web	O
services	O
.	O
</s>
<s>
These	O
techniques	O
allow	O
organizations	O
to	O
understand	O
their	O
existing	O
code	O
assets	O
(	O
using	O
discovery	O
tools	O
)	O
,	O
provide	O
new	O
user	O
and	O
application	B-Application
interfaces	O
to	O
existing	O
code	O
,	O
improve	O
workflow	O
,	O
contain	O
costs	O
,	O
minimize	O
risk	O
,	O
and	O
enjoy	O
classic	O
qualities	O
of	O
service	O
(	O
near	O
100%	O
uptime	O
,	O
security	O
,	O
scalability	O
,	O
etc	O
.	O
</s>
<s>
This	O
trend	O
also	O
invites	O
reflection	O
on	O
what	O
makes	O
legacy	B-Device
systems	I-Device
so	O
durable	O
.	O
</s>
<s>
Technologists	O
are	O
relearning	O
the	O
importance	O
of	O
sound	O
architecture	B-General_Concept
from	O
the	O
start	O
,	O
to	O
avoid	O
costly	O
and	O
risky	O
rewrites	O
.	O
</s>
<s>
The	O
most	O
common	O
legacy	B-Device
systems	I-Device
tend	O
to	O
be	O
those	O
which	O
embraced	O
well-known	O
IT	O
architectural	O
principles	O
,	O
with	O
careful	O
planning	O
and	O
strict	O
methodology	O
during	O
implementation	O
.	O
</s>
<s>
Thus	O
,	O
many	O
organizations	O
are	O
rediscovering	O
the	O
value	O
of	O
both	O
their	O
legacy	B-Device
systems	I-Device
and	O
the	O
theoretical	O
underpinnings	O
of	O
those	O
systems	O
.	O
</s>
