<s>
The	O
Ruby	B-License
License	I-License
is	O
a	O
Free	O
and	O
Open	O
Source	O
license	O
applied	O
to	O
the	O
Ruby	B-Language
programming	I-Language
language	I-Language
and	O
also	O
available	O
to	O
be	O
used	O
in	O
other	O
projects	O
.	O
</s>
<s>
It	O
contains	O
an	O
explicit	O
dual	B-License
licensing	I-License
clause	O
,	O
stating	O
that	O
software	O
subject	O
to	O
its	O
terms	O
may	O
be	O
distributed	O
under	O
either	O
the	O
terms	O
included	O
the	O
Ruby	B-License
License	I-License
itself	O
or	O
under	O
those	O
of	O
either	O
the	O
GNU	B-License
General	I-License
Public	I-License
Licence	I-License
v2	O
,	O
or	O
the	O
two-clause	O
BSD	O
License	O
(	O
depending	O
on	O
the	O
version	O
of	O
the	O
Ruby	B-License
License	I-License
used	O
)	O
.	O
</s>
<s>
The	O
license	O
is	O
typically	O
considered	O
to	O
be	O
a	O
free	B-License
software	I-License
license	I-License
due	O
to	O
the	O
presence	O
of	O
the	O
dual-licensing	B-License
clause	O
.	O
</s>
<s>
For	O
versions	O
up	O
to	O
1.9.2	O
,	O
the	O
Ruby	B-Language
programming	I-Language
language	I-Language
was	O
available	O
under	O
an	O
explicit	O
dual-licence	B-License
scheme	O
which	O
allowed	O
users	O
to	O
choose	O
between	O
a	O
dedicated	O
Ruby	B-Language
licence	O
or	O
the	O
GNU	B-License
General	I-License
Public	I-License
Licence	I-License
v2	O
(	O
GPLV2	O
)	O
,	O
which	O
is	O
one	O
of	O
the	O
most	O
common	O
free	B-License
software	I-License
licences	I-License
.	O
</s>
<s>
Starting	O
at	O
version	O
1.9.3	O
,	O
the	O
dual-licensing	B-License
clause	O
changed	O
to	O
offer	O
the	O
choice	O
of	O
the	O
FreeBSD	O
License	O
.	O
</s>
<s>
The	O
Ruby	B-License
License	I-License
has	O
unusual	O
copyleft	B-License
requirements	O
,	O
stating	O
that	O
redistributions	O
should	O
not	O
necessarily	O
be	O
under	O
the	O
terms	O
of	O
the	O
Ruby	B-License
license	I-License
,	O
but	O
placed	O
"	O
in	O
the	O
Public	O
Domain	O
or	O
otherwise	O
Freely	B-Application
Available	I-Application
"	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
modified	O
form	O
of	O
a	O
program	O
licensed	O
under	O
the	O
Ruby	B-License
license	I-License
may	O
be	O
placed	O
under	O
the	O
FreeBSD	O
License	O
,	O
which	O
is	O
a	O
non	O
copyleft	B-License
license	I-License
.	O
</s>
<s>
The	O
Ruby	B-License
License	I-License
is	O
approved	O
by	O
the	B-Operating_System
Free	I-Operating_System
Software	I-Operating_System
Foundation	I-Operating_System
and	O
is	O
considered	O
compatible	O
with	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
,	O
due	O
to	O
its	O
explicit	O
dual-licensing	B-License
clause	O
.	O
</s>
<s>
The	O
Open	O
Source	O
Initiative	O
does	O
not	O
explicitly	O
include	O
the	O
Ruby	B-License
license	I-License
as	O
a	O
certified	O
an	O
open	O
source	O
license	O
;	O
this	O
is	O
considered	O
"	O
unnecessary	O
"	O
due	O
to	O
the	O
dual	B-License
licensing	I-License
clause	O
.	O
</s>
<s>
In	O
discussion	O
over	O
the	O
change	O
of	O
the	O
dual	B-License
licensing	I-License
clause	O
on	O
the	O
debian-legal	O
mailing	O
list	O
,	O
it	O
was	O
noted	O
that	O
while	O
the	O
Ruby	B-License
license	I-License
itself	O
is	O
arguably	O
not	O
compatible	O
with	O
the	O
Debian	B-License
Free	I-License
Software	I-License
Guidelines	I-License
,	O
this	O
is	O
unimportant	O
due	O
to	O
the	O
dual-licensing	B-License
clause	O
.	O
</s>
<s>
Software	O
under	O
Ruby	B-License
license	I-License
(	O
including	O
the	O
older	O
version	O
when	O
GPLv2	O
was	O
a	O
listed	O
alternative	O
Ruby	B-Language
1.9.2	O
license	O
)	O
may	O
be	O
included	O
in	O
binary	O
form	O
within	O
an	O
Apache	O
product	O
if	O
the	O
inclusion	O
is	O
appropriately	O
labeled	O
.	O
</s>
<s>
Software	O
other	O
than	O
the	O
Ruby	B-Language
programming	I-Language
language	I-Language
itself	O
which	O
uses	O
the	O
Ruby	B-License
License	I-License
includes	O
:	O
</s>
<s>
MacRuby	B-Operating_System
,	O
an	O
implementation	O
of	O
Ruby	B-Language
1.9	O
directly	O
on	O
top	O
of	O
Mac	O
OS	O
X	O
core	O
technologies	O
such	O
as	O
the	O
Objective-C	O
runtime	O
and	O
garbage	O
collector	O
,	O
the	O
LLVM	O
compiler	O
infrastructure	O
and	O
the	O
Foundation	O
and	O
ICU	O
frameworks	O
.	O
</s>
<s>
MacRuby	B-Operating_System
contains	O
code	O
from	O
the	O
Ruby	B-Language
project	O
and	O
the	O
source	O
code	O
of	O
the	O
most	O
MacRuby	B-Operating_System
examples	O
,	O
unless	O
specified	O
,	O
are	O
covered	O
by	O
the	O
Ruby	B-License
license	I-License
.	O
</s>
