<s>
A	O
data	B-General_Concept
event	I-General_Concept
is	O
a	O
relevant	O
state	O
transition	O
defined	O
in	O
an	O
event	O
schema	O
.	O
</s>
<s>
Typically	O
,	O
event	O
schemata	O
are	O
described	O
by	O
pre	O
-	O
and	O
post	O
condition	O
for	O
a	O
single	O
or	O
a	O
set	O
of	O
data	B-General_Concept
items	I-General_Concept
.	O
</s>
<s>
In	O
contrast	O
to	O
ECA	O
(	O
Event	B-General_Concept
condition	I-General_Concept
action	I-General_Concept
)	O
,	O
which	O
considers	O
an	O
event	O
to	O
be	O
a	O
signal	O
,	O
the	O
data	B-General_Concept
event	I-General_Concept
not	O
only	O
refers	O
to	O
the	O
change	O
(	O
signal	O
)	O
,	O
but	O
describes	O
specific	O
state	O
transitions	O
,	O
which	O
are	O
referred	O
to	O
in	O
ECA	O
as	O
conditions	O
.	O
</s>
<s>
Considering	O
data	B-General_Concept
events	I-General_Concept
as	O
relevant	O
data	B-General_Concept
item	I-General_Concept
state	O
transitions	O
allows	O
defining	O
complex	O
event-reaction	O
schemata	O
for	O
a	O
database	O
.	O
</s>
<s>
Defining	O
data	B-General_Concept
event	I-General_Concept
schemata	O
for	O
relational	B-Application
databases	I-Application
is	O
limited	O
to	O
attribute	O
and	O
instance	O
events	O
.	O
</s>
<s>
Object-oriented	B-Application
databases	I-Application
also	O
support	O
collection	O
properties	O
,	O
which	O
allows	O
defining	O
changes	O
in	O
collections	O
as	O
data	B-General_Concept
events	I-General_Concept
,	O
too	O
.	O
</s>
