With no explanation, label each line with "O", "other-astronomything", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
The
young
high-mass
stars
of
this
region
constitute
the
Serpens
OB1
and
Serpens
OB2
OB
association
.
The:O
young:O
high-mass:O
stars:O
of:O
this:O
region:O
constitute:O
the:O
Serpens:other-astronomything
OB1:other-astronomything
and:O
Serpens:other-astronomything
OB2:other-astronomything
OB:other-astronomything
association:O
.:O