<s>
Survex	B-Language
is	O
free	B-License
and	I-License
open-source	I-License
cave	O
surveying	O
software	O
,	O
licensed	O
under	O
the	O
GNU	B-License
GPL	I-License
.	O
</s>
<s>
It	O
is	O
designed	O
to	O
be	O
portable	O
and	O
can	O
be	O
run	O
on	O
a	O
variety	O
of	O
platforms	O
,	O
including	O
Microsoft	B-Application
Windows	I-Application
,	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
and	O
Unix-like	B-Operating_System
.	O
</s>
<s>
Survex	B-Language
is	O
very	O
powerful	O
cave	O
survey	O
software	O
,	O
and	O
is	O
actively	O
developing	O
into	O
a	O
complete	O
cave	O
visualization	O
package	O
.	O
</s>
<s>
Survex	B-Language
has	O
no	O
arbitrary	O
limits	O
,	O
and	O
so	O
is	O
particularly	O
good	O
for	O
large	O
complicated	O
cave	O
systems	O
,	O
or	O
areas	O
where	O
you	O
need	O
to	O
see	O
the	O
relationships	O
between	O
multiple	O
cave	O
systems	O
.	O
</s>
<s>
Survex	B-Language
was	O
started	O
in	O
1990	O
by	O
Olly	O
Betts	O
and	O
Wookey	O
,	O
and	O
more	O
recently	O
Mark	O
Shinwell	O
has	O
developed	O
'	O
Aven	O
 '	O
.	O
</s>
<s>
CaveWhere	O
uses	O
cavern	O
,	O
a	O
program	O
in	O
the	O
Survex	B-Language
package	O
,	O
for	O
loop	O
closure	O
and	O
positioning	O
survey	O
stations	O
to	O
geographical	O
coordinates	O
.	O
</s>
