<s>
Portable	B-Application
Contacts	I-Application
was	O
an	O
open	O
protocol	O
for	O
developers	O
to	O
make	O
it	O
easier	O
for	O
developers	O
to	O
give	O
their	O
users	O
a	O
secure	O
way	O
to	O
access	O
the	O
address	B-Operating_System
books	I-Operating_System
and	O
friends	B-Protocol
lists	I-Protocol
they	O
have	O
built	O
up	O
all	O
over	O
the	O
web	O
.	O
</s>
<s>
The	O
goal	O
of	O
the	O
project	O
was	O
to	O
increase	O
data	B-Application
portability	I-Application
by	O
creating	O
a	O
common	O
and	O
open	O
specification	O
to	O
bridge	O
proprietary	O
contacts	O
Application	B-Application
programming	I-Application
interfaces	I-Application
(	O
API	B-Application
)	O
such	O
as	O
Google	O
's	O
GData	B-Application
Contacts	O
API	B-Application
,	O
Yahoo	O
's	O
Address	B-Operating_System
Book	I-Operating_System
API	B-Application
,	O
and	O
Microsoft	O
's	O
Live	O
Contacts	O
API	B-Application
.	O
</s>
<s>
It	O
combines	O
OAuth	O
,	O
XRDS-Simple	O
and	O
a	O
wire-format	O
based	O
on	O
vCard	O
harmonized	O
with	O
schema	O
from	O
OpenSocial	B-Application
.	O
</s>
<s>
The	O
editor	O
of	O
Portable	B-Application
Contacts	I-Application
specification	O
was	O
Joseph	O
Smarr	O
of	O
Plaxo	O
and	O
the	O
project	O
co-maintained	O
by	O
Chris	O
Messina	O
.	O
</s>
<s>
Portable	B-Application
Contacts	I-Application
was	O
used	O
by	O
services	O
such	O
as	O
Google	O
Contacts	O
,	O
Windows	B-Library
Live	I-Library
Messenger	I-Library
Connect	I-Library
,	O
as	O
well	O
as	O
other	O
specification	O
such	O
as	O
OStatus	B-Application
.	O
</s>
