<s>
Resources	B-General_Concept
,	I-General_Concept
events	I-General_Concept
,	I-General_Concept
agents	I-General_Concept
(	O
REA	O
)	O
is	O
a	O
model	O
of	O
how	O
an	O
accounting	O
system	O
can	O
be	O
re-engineered	O
for	O
the	O
computer	O
age	O
.	O
</s>
<s>
REA	O
is	O
a	O
popular	O
model	O
in	O
teaching	O
accounting	B-Application
information	I-Application
systems	I-Application
(	O
AIS	O
)	O
,	O
but	O
it	O
is	O
rare	O
in	O
business	O
practice	O
.	O
</s>
<s>
Most	O
companies	O
cannot	O
easily	O
dismantle	O
their	O
legacy	B-Device
data	O
warehouse	O
systems	O
or	O
are	O
unwilling	O
to	O
do	O
so	O
.	O
</s>
<s>
Workday	O
,	O
Inc.	O
,	O
IBM	B-Application
Scalable	I-Application
Architecture	I-Application
for	I-Application
Financial	I-Application
Reporting	I-Application
,	O
REATechnology	O
,	O
and	O
ISO	O
15944-4	O
are	O
exceptions	O
.	O
</s>
<s>
Many	O
general	O
ledger	B-Language
accounts	O
also	O
disappear	O
,	O
at	O
least	O
as	O
persistent	O
objects	O
;	O
e.g.	O
,	O
accounts	O
receivable	O
or	O
accounts	O
payable	O
.	O
</s>
<s>
In	O
computer	B-General_Concept
science	I-General_Concept
terms	O
,	O
REA	O
is	O
an	O
ontology	O
.	O
</s>
<s>
REA	O
systems	O
have	O
usually	O
been	O
modeled	O
as	O
relational	B-Application
databases	I-Application
with	O
entity-relationship	B-Architecture
diagrams	I-Architecture
,	O
though	O
this	O
is	O
not	O
compulsory	O
.	O
</s>
<s>
The	O
philosophy	O
of	O
REA	O
draws	O
on	O
the	O
idea	O
of	O
reusable	O
Design	O
Patterns	O
,	O
though	O
REA	O
patterns	O
are	O
used	O
to	O
describe	O
databases	O
rather	O
than	O
object-oriented	B-Language
programs	I-Language
,	O
and	O
are	O
quite	O
different	O
from	O
the	O
23	O
canonical	O
patterns	O
in	O
the	O
original	O
designs	O
pattern	O
book	O
by	O
Gamma	O
et	O
al	O
.	O
</s>
<s>
Here	O
is	O
an	O
example	O
of	O
the	O
basic	O
REA	O
pattern	O
shown	O
as	O
an	O
E-R	B-Architecture
diagram	I-Architecture
:	O
</s>
<s>
(	O
2006	O
)	O
is	O
an	O
advanced	O
reference	O
for	O
computer	B-General_Concept
scientists	I-General_Concept
.	O
</s>
<s>
REA	O
is	O
a	O
continuing	O
influence	O
on	O
the	O
electronic	O
commerce	O
standard	O
ebXML	B-Language
,	O
with	O
W	O
.	O
McCarthy	O
actively	O
involved	O
in	O
the	O
standards	O
committee	O
.	O
</s>
<s>
REA	O
is	O
now	O
recognised	O
by	O
The	B-Application
Open	I-Application
Group	I-Application
within	O
the	O
TOGAF	O
standard	O
(	O
an	O
industry	O
standard	O
enterprise	O
framework	O
)	O
,	O
as	O
one	O
of	O
the	O
modelling	O
tools	O
which	O
is	O
useful	O
for	O
modelling	O
business	O
processes	O
.	O
</s>
