<s>
Initially	O
,	O
temporal	B-Language
expressions	I-Language
were	O
considered	O
a	O
type	O
of	O
named	B-General_Concept
entities	I-General_Concept
and	O
their	O
identification	O
was	O
part	O
of	O
the	O
named	B-General_Concept
entity	I-General_Concept
recognition	I-General_Concept
task	O
.	O
</s>
<s>
Timex	O
evaluation	O
is	O
now	O
evaluated	O
in	O
two	O
major	O
temporal	O
annotation	O
challenges	O
:	O
TempEval	O
and	O
i2b2	O
,	O
both	O
of	O
which	O
prefer	O
the	O
TimeML-level	O
TIMEX3	O
standard	O
.	O
</s>
