Request for the addition of a manually operated "Backing" Ping

It is a simple request, but an important one. I often find situations where one player backs and his/her opponent roams in response. Laners, who are focused on their own situations, often don't notice until it's too late and get punished.

The ability to quickly express that someone is backing to base, and to therefore be on alert for ganks from their lane opponent, is one of the major communications we can do freely on a microphone, but lack in the ping menu.

The missing ping is often used as a poor substitute, but it's limited to being reactive in nature. Often times the missing ping is called in vain, as the opponent is already in motion and the damage already done. A backing ping could be used more proactively by players, as they commit to backing and before the opponent is fully freed up.

Being able to have a distinctly toned ping for backing would provide a sorely needed function to alert players that a lane is being temporarily abandoned and to be on guard for ambushes. Such a feature is one i'd love to see added.