<s>
Jetpack	B-Application
was	O
a	O
working	O
group	O
which	O
wrote	O
a	O
software	B-Application
development	I-Application
kit	I-Application
for	O
Firefox	B-Operating_System
add-ons	I-Operating_System
.	O
</s>
<s>
They	O
produced	O
the	O
Add-on	B-Operating_System
SDK	O
,	O
a	O
set	O
of	O
APIs	B-Application
,	O
a	O
runtime	B-Device
,	O
and	O
a	O
command-line	O
tool	O
for	O
creating	O
and	O
running	O
add-ons	B-Operating_System
,	O
and	O
the	O
Add-on	B-Operating_System
Builder	O
,	O
a	O
Web-based	O
integrated	B-Application
development	I-Application
environment	I-Application
which	O
used	O
the	O
SDK	O
.	O
</s>
<s>
Add-ons	B-Operating_System
developed	O
with	O
the	O
SDK	O
were	O
written	O
in	O
HTML	B-Language
,	O
CSS	B-Language
,	O
and	O
JavaScript	B-Language
using	O
CommonJS	B-Language
conventions	O
.	O
</s>
<s>
They	O
did	O
not	O
require	O
the	O
user	O
to	O
restart	O
Firefox	B-Application
when	O
they	O
were	O
installed	O
or	O
uninstalled	O
.	O
</s>
<s>
The	O
SDK	O
's	O
APIs	B-Application
were	O
high-level	O
,	O
task-oriented	O
,	O
and	O
designed	O
to	O
insulate	O
developers	O
from	O
changes	O
across	O
Firefox	B-Application
versions	O
.	O
</s>
<s>
Mozillians	O
running	O
the	O
project	O
made	O
a	O
tool	O
called	O
the	O
Jetpack	B-Application
Prototype	O
.	O
</s>
<s>
APIs	B-Application
provided	O
by	O
the	O
Jetpack	B-Application
Prototype	O
were	O
not	O
compatible	O
with	O
the	O
Add-on	B-Operating_System
SDK	O
.	O
</s>
