<s>
The	O
PHP	B-Language
License	I-Language
is	O
the	O
open-source	O
license	O
under	O
which	O
the	O
PHP	B-Application
scripting	O
language	O
is	O
released	O
.	O
</s>
<s>
The	O
PHP	B-Language
License	I-Language
is	O
designed	O
to	O
encourage	O
widespread	O
adoption	O
of	O
the	O
source	O
code	O
.	O
</s>
<s>
Version	O
3	O
of	O
PHP	B-Application
used	O
a	O
dual	B-License
license	I-License
—	O
PHP	B-Application
3	O
's	O
source	O
is	O
available	O
under	O
either	O
the	O
PHP	B-Language
License	I-Language
or	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
(	O
GPL	B-License
)	O
.	O
</s>
<s>
This	O
practice	O
was	O
discontinued	O
as	O
of	O
PHP	B-Application
4	O
,	O
with	O
PHP	B-Application
's	O
developers	O
citing	O
the	O
restrictions	O
on	O
reuse	O
associated	O
with	O
the	O
GPL	B-License
's	O
copyleft	B-License
enforcement	O
as	O
being	O
the	O
reason	O
for	O
dropping	O
it	O
.	O
</s>
<s>
The	O
Zend	B-Language
Engine	I-Language
,	O
the	O
core	O
of	O
the	O
PHP	B-Application
interpreter	I-Application
,	O
is	O
separately	O
licensed	O
under	O
the	O
similar	O
Zend	B-Language
Engine	I-Language
License	O
,	O
which	O
contains	O
similar	O
naming	O
restrictions	O
to	O
the	O
PHP	B-Language
license	I-Language
(	O
applying	O
to	O
the	O
names	O
"	O
Zend	O
"	O
and	O
"	O
Zend	B-Language
Engine	I-Language
"	O
)	O
,	O
and	O
a	O
clause	O
requiring	O
advertising	O
materials	O
to	O
mention	O
its	O
use	O
.	O
</s>
<s>
The	O
PHP	B-Language
License	I-Language
is	O
an	O
open	O
source	O
license	O
according	O
to	O
the	O
Open	O
Source	O
Initiative	O
,	O
and	O
a	O
non-copyleft	B-License
free	B-Application
software	I-Application
license	O
according	O
to	O
the	B-Operating_System
Free	I-Operating_System
Software	I-Operating_System
Foundation	I-Operating_System
.	O
</s>
<s>
The	O
license	O
is	O
GPL-incompatible	O
due	O
to	O
restrictions	O
on	O
the	O
usage	O
of	O
the	O
term	O
PHP	B-Application
.	O
</s>
<s>
Debian	O
maintainers	O
have	O
had	O
a	O
long-standing	O
discussion	O
(	O
since	O
at	O
least	O
2005	O
)	O
about	O
the	O
validity	O
of	O
the	O
PHP	B-Language
license	I-Language
.	O
</s>
<s>
Expressed	O
concerns	O
include	O
that	O
the	O
license	O
"	O
contains	O
statements	O
about	O
the	O
software	O
it	O
covers	O
that	O
are	O
specific	O
to	O
distributing	O
PHP	B-Application
itself	O
"	O
,	O
which	O
,	O
for	O
other	O
software	O
than	O
PHP	B-Application
itself	O
therefore	O
would	O
be	O
"	O
false	O
statements	O
"	O
.	O
</s>
<s>
Debian	O
has	O
a	O
specific	O
policy	O
for	O
the	O
license	O
(	O
and	O
requires	O
a	O
statement	O
in	O
debian/copyright	O
file	O
when	O
it	O
is	O
used	O
)	O
:	O
"	O
The	O
PHP	B-Language
license	I-Language
must	O
only	O
be	O
used	O
for	O
PHP	B-Application
and	O
PHP	B-Application
add-ons.	O
"	O
</s>
