<s>
The	O
Lightning	B-Language
project	O
,	O
announced	O
on	O
December	O
22	O
,	O
2004	O
,	O
and	O
developed	O
by	O
the	B-Operating_System
Mozilla	I-Operating_System
Foundation	I-Operating_System
,	O
produces	O
an	O
extension	O
that	O
adds	O
calendar	B-Application
and	O
scheduling	O
functionality	O
to	O
the	O
Mozilla	B-Application
Thunderbird	I-Application
mail	O
and	O
newsgroup	O
client	O
and	O
SeaMonkey	B-Language
internet	I-Language
suite	I-Language
.	O
</s>
<s>
Lightning	B-Language
is	O
an	O
iCalendar	O
compatible	O
calendar	B-Application
.	O
</s>
<s>
Unlike	O
the	O
discontinued	O
Mozilla	B-Language
Sunbird	I-Language
and	O
Mozilla	B-Application
Calendar	I-Application
extension	I-Application
,	O
Lightning	B-Language
integrates	O
tightly	O
with	O
Thunderbird	B-Application
.	O
</s>
<s>
Lightning	B-Language
is	O
available	O
in	O
32-bit	O
and	O
64-bit	O
versions	O
for	O
Windows	O
,	O
macOS	B-Application
and	O
Linux	B-Application
,	O
and	O
is	O
installed	O
by	O
default	O
on	O
Thunderbird	B-Application
.	O
</s>
<s>
Version	O
0.9	O
was	O
the	O
last	O
planned	O
release	O
for	O
Thunderbird	B-Application
2	O
.	O
</s>
<s>
A	O
calendar	B-Application
was	O
originally	O
to	O
be	O
fully	O
integrated	O
into	O
Thunderbird	B-Application
3	O
,	O
but	O
those	O
plans	O
were	O
changed	O
due	O
to	O
concerns	O
with	O
the	O
product	O
's	O
maturity	O
and	O
level	O
of	O
support	O
.	O
</s>
<s>
Lightning	B-Language
1.0b2	O
is	O
compatible	O
with	O
Thunderbird	B-Application
3.1	O
,	O
Lightning	B-Language
1.0b5	O
is	O
compatible	O
with	O
Thunderbird	B-Application
5	O
and	O
6	O
,	O
and	O
Lightning	B-Language
1.0b7	O
is	O
compatible	O
with	O
Thunderbird	B-Application
7	O
.	O
</s>
<s>
Lightning	B-Language
1.0	O
was	O
released	O
to	O
the	O
public	O
on	O
November	O
7	O
,	O
2011	O
.	O
</s>
<s>
It	O
was	O
released	O
alongside	O
Thunderbird	B-Application
8.0	O
.	O
</s>
<s>
Following	O
that	O
,	O
every	O
Thunderbird	B-Application
release	O
has	O
been	O
accompanied	O
by	O
a	O
compatible	O
Lightning	B-Language
point	O
release	O
.	O
</s>
<s>
Lightning	B-Language
finally	O
started	O
shipping	O
with	O
Thunderbird	B-Application
with	O
version	O
4.0	O
.	O
</s>
<s>
As	O
of	O
21	O
October	O
,	O
2018	O
,	O
Lightning	B-Language
5.4	O
is	O
incompatible	O
with	O
the	O
latest	O
release	O
of	O
Thunderbird	B-Application
60.2.1	O
.	O
</s>
<s>
Sun	O
Microsystems	O
contributed	O
significantly	O
to	O
the	O
Lightning	B-Language
Project	O
to	O
provide	O
users	O
with	O
an	O
alternative	O
free	O
and	O
open-source	O
choice	O
to	O
Microsoft	B-Application
Office	I-Application
by	O
combining	O
OpenOffice.org	B-Application
and	O
Thunderbird	B-Application
with	O
the	O
Lightning	B-Language
Extension	O
.	O
</s>
<s>
In	O
addition	O
to	O
general	O
bug-fixing	O
,	O
Sun	O
focused	O
on	O
calendar	B-Application
views	O
,	O
team/collaboration	O
features	O
and	O
support	O
for	O
the	O
Sun	B-Application
Java	I-Application
System	I-Application
Calendar	I-Application
Server	I-Application
.	O
</s>
