<s>
A	O
chord	B-Operating_System
is	O
a	O
concurrency	O
construct	O
available	O
in	O
Polyphonic	B-Language
C♯	I-Language
and	O
Cω	B-Language
inspired	O
by	O
the	O
join	O
pattern	O
of	O
the	O
join-calculus	B-Language
.	O
</s>
<s>
A	O
chord	B-Operating_System
is	O
a	O
function	O
body	O
that	O
is	O
associated	O
with	O
multiple	O
function	O
headers	O
and	O
cannot	O
execute	O
until	O
all	O
function	O
headers	O
are	O
called	O
.	O
</s>
<s>
Cω	B-Language
defines	O
two	O
types	O
of	O
functions	O
synchronous	O
and	O
asynchronous	O
.	O
</s>
