<s>
The	O
Binary	O
Universal	O
Form	O
for	O
the	O
Representation	O
of	O
meteorological	O
data	O
(	O
BUFR	B-Application
)	O
is	O
a	O
binary	O
data	O
format	O
maintained	O
by	O
the	O
World	O
Meteorological	O
Organization	O
(	O
WMO	O
)	O
.	O
</s>
<s>
The	O
latest	O
version	O
is	O
BUFR	B-Application
Edition	O
4	O
.	O
</s>
<s>
BUFR	B-Application
Edition	O
3	O
is	O
also	O
considered	O
current	O
for	O
operational	O
use	O
.	O
</s>
<s>
BUFR	B-Application
was	O
created	O
in	O
1988	O
with	O
the	O
goal	O
of	O
replacing	O
the	O
WMO	O
's	O
dozens	O
of	O
character-based	O
,	O
position-driven	O
meteorological	O
codes	O
,	O
such	O
as	O
SYNOP	B-Application
(	O
surface	O
observations	O
)	O
,	O
TEMP	B-Application
(	O
upper	O
air	O
soundings	O
)	O
and	O
CLIMAT	B-Application
(	O
monthly	O
climatological	O
data	O
)	O
.	O
</s>
<s>
BUFR	B-Application
was	O
designed	O
to	O
be	O
portable	O
,	O
compact	O
,	O
and	O
universal	O
.	O
</s>
<s>
In	O
the	O
WMO	O
terminology	O
,	O
BUFR	B-Application
belongs	O
to	O
the	O
category	O
of	O
table-driven	O
code	O
forms	O
,	O
where	O
the	O
meaning	O
of	O
data	O
elements	O
is	O
determined	O
by	O
referring	O
to	O
a	O
set	O
of	O
tables	O
that	O
are	O
kept	O
and	O
maintained	O
separately	O
from	O
the	O
message	O
itself	O
.	O
</s>
<s>
BUFR	B-Application
is	O
a	O
complex	O
format	O
that	O
can	O
be	O
difficult	O
to	O
use	O
and	O
it	O
presents	O
some	O
weaknesses	O
.	O
</s>
<s>
The	O
introduction	O
of	O
BUFR	B-Application
format	O
led	O
to	O
data	O
"	O
disparition	O
"	O
and	O
many	O
formatting	O
errors	O
.	O
</s>
<s>
A	O
BUFR	B-Application
message	O
is	O
composed	O
of	O
six	O
sections	O
,	O
numbered	O
zero	O
through	O
five	O
.	O
</s>
<s>
Section	O
3	O
contains	O
a	O
sequence	O
of	O
so-called	O
descriptors	O
that	O
define	O
the	O
form	O
and	O
contents	O
of	O
the	O
BUFR	B-Application
data	O
product	O
.	O
</s>
<s>
(	O
See	O
below	O
for	O
a	O
brief	O
overview	O
of	O
the	O
different	O
kinds	O
of	O
descriptors	O
;	O
refer	O
to	O
the	O
WMO	O
Guide	O
on	O
BUFR	B-Application
for	O
further	O
detail	O
.	O
)	O
</s>
<s>
The	O
sequence	O
of	O
descriptors	O
in	O
Section	O
3	O
could	O
be	O
understood	O
as	O
the	O
template	O
of	O
the	O
BUFR	B-Application
message	O
.	O
</s>
<s>
Given	O
a	O
set	O
of	O
BUFR	B-Application
messages	O
,	O
the	O
values	O
contained	O
in	O
Section	O
4	O
may	O
differ	O
from	O
one	O
message	O
to	O
the	O
next	O
,	O
but	O
their	O
ordering	O
and	O
structure	O
will	O
be	O
kept	O
predictable	O
if	O
the	O
template	O
provided	O
in	O
Section	O
3	O
remains	O
unchanged	O
.	O
</s>
<s>
Such	O
templates	O
can	O
then	O
be	O
used	O
to	O
standardize	O
the	O
content	O
and	O
structure	O
of	O
BUFR	B-Application
data	O
products	O
.	O
</s>
<s>
The	O
WMO	O
has	O
released	O
a	O
number	O
of	O
BUFR	B-Application
templates	O
for	O
surface	O
and	O
upper	O
air	O
observational	O
data	O
.	O
</s>
<s>
Element	O
descriptors	O
classes	O
1	O
through	O
9	O
have	O
the	O
special	O
property	O
of	O
remaining	O
in	O
effect	O
from	O
the	O
moment	O
they	O
appear	O
throughout	O
the	O
remainder	O
of	O
the	O
BUFR	B-Application
template	O
,	O
unless	O
contradicted	O
or	O
cancelled	O
.	O
</s>
<s>
In	O
practice	O
,	O
class	O
1	O
through	O
9	O
descriptors	O
are	O
used	O
for	O
spatial	O
,	O
temporal	O
and	O
other	O
meta-data	O
that	O
is	O
applicable	O
to	O
the	O
core	O
data	O
of	O
the	O
BUFR	B-Application
message	O
.	O
</s>
<s>
All	O
element	O
descriptors	O
are	O
defined	O
in	O
a	O
section	O
of	O
the	O
BUFR	B-Application
specification	O
known	O
as	O
"	O
Table	O
B	O
"	O
.	O
</s>
<s>
The	O
addition	O
of	O
new	O
element	O
descriptors	O
in	O
Table	O
B	O
does	O
not	O
require	O
changes	O
to	O
the	O
BUFR	B-Application
software	O
specification	O
.	O
</s>
<s>
This	O
is	O
a	O
very	O
powerful	O
operation	O
that	O
introduces	O
loop-like	O
structures	O
in	O
BUFR	B-Application
templates	O
.	O
</s>
<s>
These	O
descriptors	O
are	O
defined	O
in	O
a	O
section	O
of	O
the	O
BUFR	B-Application
specification	O
known	O
as	O
"	O
Table	O
C	O
"	O
.	O
</s>
<s>
The	O
addition	O
of	O
new	O
operator	O
descriptors	O
in	O
Table	O
C	O
does	O
require	O
changes	O
to	O
the	O
BUFR	B-Application
software	O
specification	O
,	O
and	O
therefore	O
leads	O
to	O
a	O
new	O
BUFR	B-Application
Edition	O
Number	O
.	O
</s>
<s>
These	O
descriptors	O
are	O
defined	O
in	O
a	O
section	O
of	O
the	O
BUFR	B-Application
specification	O
known	O
as	O
"	O
Table	O
D	O
"	O
.	O
</s>
<s>
The	O
data	O
structure	O
established	O
in	O
the	O
Section	O
3	O
template	O
may	O
be	O
re-used	O
multiple	O
times	O
within	O
a	O
single	O
BUFR	B-Application
message	O
.	O
</s>
