Why is there no side-to-side Sine behavior?

This could be a suggestion I guess, though really I'm just curious if there's a particular reason for it. Sine behavior parameters include all kinds of options from X/Y movement, to angle and value. And then at the end there's Forwards/backwards movement... but no side-to-side movement? Seems like it should naturally have been added with forwards/backwards, so was it omitted?

Um, you are aware that "Forwards/Backwards" moves the object forwards and backwards on its current angle, right?

When the object is facing down, it moves downwards and upwards, when it's facing to the right, it moves to the right and to the left.

Horizontal?

Well yeah, what I mean is, a movement similar to forwards/backwards, except instead of moving an object back and forth on the object's angle, it moves it side-to-side perpendicular to the object's current angle. So if the object is facing right, it moves up and down, if it's facing up, it moves right and left, etc.

It just seemed odd to me that there's a backwards/forwards option that takes into account an object's angle, but no side-to-side equivalent as it looks like a natural next step.