Do you have a source? I can only find out of bounds. There is no clarity to sideways or backwards that I could locate. Generally speaking backwards typically happens when forward progress stops in the field of play and the player is pushed back. Officials will keep that clock moving in that scenario.
I’ve seen a couple times where a player runs backwards to get out of bounds to elude hits or defenders.
No source but from watching games and listening to announcers - that's the rule.
As to going backwards, that is wholly contingent on the player running backwards when they go out of bounds.
I remember Beckham purposely running backwards when he went out of bounds to keep the clock running when they had a lead.
If forward progress is stopped while inbounds - the refs will keep the clock running even if the runner is pushed out of bounds.
Depends on if the runner's forward progress is stopped. Judgement call by the refs.
