<s>
In	O
mathematics	O
,	O
Newick	B-Data_Structure
tree	I-Data_Structure
format	I-Data_Structure
(	O
or	O
Newick	B-Data_Structure
notation	I-Data_Structure
or	O
New	B-Data_Structure
Hampshire	I-Data_Structure
tree	I-Data_Structure
format	I-Data_Structure
)	O
is	O
a	O
way	O
of	O
representing	O
graph-theoretical	O
trees	O
with	O
edge	O
lengths	O
using	O
parentheses	O
and	O
commas	O
.	O
</s>
<s>
The	O
adopted	O
format	O
is	O
a	O
generalization	O
of	O
the	O
format	O
developed	O
by	O
Meacham	O
in	O
1984	O
for	O
the	O
first	O
tree-drawing	O
programs	O
in	O
Felsenstein	O
's	O
PHYLIP	B-Application
package	O
.	O
</s>
<s>
Newick	B-Data_Structure
format	I-Data_Structure
is	O
typically	O
used	O
for	O
tools	O
like	O
PHYLIP	B-Application
and	O
is	O
a	O
minimal	O
definition	O
for	O
a	O
phylogenetic	O
tree	O
.	O
</s>
<s>
When	O
an	O
unrooted	O
tree	O
is	O
represented	O
in	O
Newick	B-Data_Structure
notation	I-Data_Structure
,	O
an	O
arbitrary	O
node	O
is	O
chosen	O
as	O
its	O
root	O
.	O
</s>
<s>
A	O
grammar	O
for	O
parsing	O
the	O
Newick	B-Data_Structure
format	I-Data_Structure
(	O
roughly	O
based	O
on	O
)	O
:	O
</s>
