Unquoted '':
start:
||
end
start:
||
end
start:
||
end
start:
||
end
start:
||
||
end

Unquoted "":
start:
||
end
start:
||
end
start:
||
end
start:
||
end
start:
||
||
end

Quoted '':
start:
|''|
end
start:
|'' |
end
start:
| ''|
end
start:
| '' |
end
start:
|'' ''|
end

Quoted "":
start:
||
end
start:
| |
end
start:
| |
end
start:
|  |
end
start:
| |
end