abstract
accident
background
blue
boat
border
break
cloud
color
cross
crossroad
danger
data
deck
design
direction
end
ferry
forbidden
frame
graphic
halt
icon
idea
illustration
information
metal
nobody
object
ocean
prohibition
radar
red
roadblock
rope
round
safety
sea
ship
sign
signal
sky
stop
stopsign
symbol
technology
text
transport
transportation
travel
trip
warning
white