<s>
The	O
VA	B-Language
Kernel	I-Language
is	O
a	O
set	O
of	O
programs	O
,	O
developed	O
by	O
the	O
Department	O
of	O
Veterans	O
Affairs	O
of	O
the	O
United	O
States	O
Government	O
,	O
which	O
provide	O
an	O
operating	O
system	O
and	O
MUMPS	B-Language
implementation	O
independent	O
abstraction	O
to	O
the	O
VistA	B-Application
Hospital	O
Information	O
System	O
.	O
</s>
<s>
These	O
programs	O
(	O
called	O
'	O
routines	O
 '	O
in	O
MUMPS	B-Language
)	O
are	O
the	O
only	O
programs	O
which	O
are	O
expected	O
to	O
not	O
be	O
written	O
in	O
ANSI	O
Standard	O
MUMPS	B-Language
.	O
</s>
<s>
The	O
MUMPS	B-Language
language	I-Language
used	O
in	O
the	O
kernel	O
is	O
amazingly	O
simple	O
,	O
consisting	O
of	O
a	O
single	O
language	O
(	O
MUMPS	B-Language
)	O
,	O
a	O
single	O
data	O
type	O
(	O
string	O
)	O
,	O
a	O
single	O
data	O
storage	O
mechanism	O
(	O
global	O
arrays	O
stored	O
on	O
disk	O
)	O
,	O
19	O
commands	O
and	O
22	O
functions	O
.	O
</s>
<s>
MUMPS	B-Language
is	O
a	O
symbolic	O
language	O
with	O
linguistic	O
roots	O
closer	O
to	O
LISP	B-Language
than	O
Fortran	B-Application
or	O
COBOL	B-Application
.	O
</s>
<s>
Because	O
of	O
this	O
simple	O
software	O
layer	O
,	O
the	O
VistA	B-Application
software	O
architecture	O
has	O
been	O
able	O
to	O
adapt	O
to	O
changing	O
hardware	O
environments	O
over	O
the	O
decades	O
with	O
only	O
the	O
minimum	O
amount	O
of	O
software	O
changes	O
at	O
higher	O
levels	O
of	O
abstraction	O
.	O
</s>
<s>
The	O
CHCS	B-Application
system	O
and	O
the	O
RPMS	B-Application
system	O
have	O
a	O
Kernel	O
as	O
well	O
,	O
which	O
provides	O
a	O
similar	O
degree	O
of	O
support	O
to	O
those	O
systems	O
as	O
the	O
VA	B-Language
Kernel	I-Language
does	O
to	O
VistA	B-Application
.	O
</s>
<s>
The	O
VA	B-Language
Kernel	I-Language
provides	O
abstractions	O
for	O
:	O
</s>
