With no explanation, label each line with "O", "product-weapon", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport" or "building-hospital" preceded by ":".
This
action
also
marked
the
first
use
of
the
new
,
unguided
R4M
rockets
.
This:O
action:O
also:O
marked:O
the:O
first:O
use:O
of:O
the:O
new:O
,:O
unguided:O
R4M:product-weapon
rockets:O
.:O