abstract
ahead
alert
attention
background
caution
circle
cutout
danger
do
do not enter
enter
entrance
entry
forbid
forbidden
hazard
icon
iron
isolated
keep
label
law
limit
mandatory
no
not
old
outside
photo
prohibited
red
restriction
retro
road sign
round
rule
safety
shape
sign
stop
symbol
symbolic
text
transportation
urban
vintage
warning
wrong