The category "<displayable_thing>" can be expressed as follows:
<displayable_line> lines
altitude
altitudes
bearing
bearings
buildings
call sign
call signs
craters
depth
ditches
dragons teeth
fighting positions
heading
headings
miclic line
miclic scorch
orientation
orientations
railroads
roads
rock drops
soils
speed
speeds
towns
track
track number
track numbers
tracks
trees
unit call sign
unit call signs
water
water and soils
wire