Since 1970 the map has used a reversed (red on white) British Rail "double arrow" beside the station name to indicate mainline interchanges.
They use modern, simple, clean lines, and double yellow arrows point up on the bottle, meant to convey the "next step" or "moving forward."
Within the image, a double arrow indicates two inverted terms of the first proportion.
The green and gold livery on vehicles was retained, though with a new "double arrow" logo.
A new swallow logo 'to symbolise grace and speed' replaced the double arrow.
This can be illustrated as follows (here the double arrow indicates a Spin-1/2 orientation, the single arrows for direction of motion):
The double arrow stands symbolizes 'if and only if,' 'necessary and sufficient' conditions.
If the value after the double arrow is a very large number itself, the above can recursively be applied to that value.
The two other creatures shot out from him, like a double arrow loosed from a bow, still linked with each other.
Some locomotives, including 20227, were repainted in the Railfreight grey livery with red sole bars, yellow ends and large double arrows on the sides.
