advice
aged
beware
black
black and white
bone
business
button
caution
company
danger
dead
death
design
dirty
dot
graphic
grunge
halftone
hazard
icon
index
indication
info
isolated
macro
mark
old
outline
pictogram
pirate
pixel
print
retro
risk
scull
seal
sign
signal
single color
skeleton
skull
smile
spot
step back
stop
stylized
symbol
texture
triangle
virus
warning