<s>
In	O
the	O
world	O
of	O
software	O
development	O
,	O
maintenance	B-General_Concept
mode	I-General_Concept
refers	O
to	O
a	O
point	O
in	O
a	O
computer	B-Application
program	I-Application
's	O
life	O
when	O
it	O
has	O
reached	O
all	O
of	O
its	O
goals	O
and	O
is	O
generally	O
considered	O
to	O
be	O
"	O
complete	O
"	O
and	O
bug-free	O
.	O
</s>
<s>
The	O
term	O
can	O
also	O
refer	O
to	O
the	O
point	O
in	O
a	O
software	B-Application
product	I-Application
's	O
evolution	O
when	O
it	O
is	O
no	O
longer	O
competitive	O
with	O
other	O
products	O
or	O
current	O
with	O
regard	O
to	O
the	O
technology	O
environment	O
it	O
operates	O
within	O
.	O
</s>
<s>
In	O
both	O
cases	O
,	O
continued	O
development	O
is	O
deemed	O
unnecessary	O
or	O
ill-advised	O
,	O
but	O
occasional	O
bug	B-Error_Name
fixes	O
and	O
security	O
patches	O
are	O
still	O
issued	O
,	O
hence	O
the	O
term	O
maintenance	B-General_Concept
mode	I-General_Concept
.	O
</s>
<s>
Maintenance	B-General_Concept
mode	I-General_Concept
often	O
transitions	O
to	O
abandonware	O
.	O
</s>
<s>
Sometimes	O
,	O
when	O
a	O
popular	O
free	B-Application
software	I-Application
project	O
undergoes	O
a	O
major	O
overhaul	O
,	O
the	O
pre-overhaul	O
version	O
is	O
kept	O
active	O
and	O
put	O
into	O
maintenance	B-General_Concept
mode	I-General_Concept
because	O
it	O
will	O
still	O
be	O
widely	O
used	O
in	O
production	O
for	O
the	O
foreseeable	O
future	O
.	O
</s>
<s>
Project	B-Application
forks	I-Application
can	O
also	O
spawn	O
from	O
programs	O
that	O
go	O
into	O
maintenance	B-General_Concept
mode	I-General_Concept
too	O
soon	O
or	O
have	O
enough	O
developer	O
support	O
for	O
a	O
more	O
advanced	O
version	O
.	O
</s>
<s>
A	O
good	O
example	O
of	O
this	O
is	O
the	O
vi	B-Application
editor	I-Application
,	O
which	O
was	O
in	O
maintenance	B-General_Concept
mode	I-General_Concept
and	O
forked	O
into	O
Vi	B-Application
IMproved	I-Application
.	O
</s>
<s>
The	O
Vim	B-Application
fork	B-Application
has	O
many	O
useful	O
features	O
that	O
vi	B-Application
does	O
not	O
,	O
such	O
as	O
syntax	O
highlighting	O
and	O
the	O
ability	O
to	O
have	O
multiple	O
open	O
buffers	B-General_Concept
.	O
</s>
