<s>
Extended	B-Language
ML	I-Language
is	O
a	O
wide-spectrum	O
language	O
based	O
on	O
ML	B-Language
,	O
covering	O
both	O
specification	B-Application
and	O
implementation	O
.	O
</s>
<s>
It	O
extends	O
the	O
syntax	O
of	O
ML	B-Language
to	O
include	O
axioms	O
,	O
which	O
do	O
not	O
need	O
to	O
be	O
executable	O
but	O
can	O
rigorously	O
specify	O
the	O
behavior	O
of	O
the	O
program	O
.	O
</s>
<s>
With	O
this	O
addition	O
the	O
language	O
can	O
be	O
used	O
for	O
stepwise	O
refinement	O
,	O
proceeding	O
gradually	O
from	O
an	O
initial	O
formal	B-Application
specification	I-Application
to	O
eventually	O
yield	O
an	O
executable	O
Standard	B-Language
ML	I-Language
program	O
.	O
</s>
<s>
Correctness	O
of	O
the	O
final	O
executable	O
with	O
respect	O
to	O
the	O
original	O
specification	B-Application
can	O
then	O
be	O
established	O
by	O
proving	O
the	O
correctness	O
of	O
each	O
of	O
the	O
refinement	O
steps	O
.	O
</s>
<s>
Extended	B-Language
ML	I-Language
is	O
used	O
for	O
research	O
into	O
and	O
teaching	O
of	O
formal	B-Architecture
program	O
development	O
and	O
specification	B-Application
and	O
research	O
into	O
automatic	O
program	O
verification	O
.	O
</s>
<s>
Extended	B-Language
ML	I-Language
is	O
neither	O
related	O
to	O
the	O
programming	O
language	O
Extensible	O
ML	B-Language
(	O
other	O
than	O
being	O
similarly	O
derived	O
from	O
ML	B-Language
)	O
,	O
nor	O
to	O
the	O
specification	B-Application
language	I-Application
Extensible	B-Protocol
Markup	I-Protocol
Language	I-Protocol
(	O
XML	B-Protocol
)	O
.	O
</s>
