What's the forward and reverse zooming?

Question

Is there a tradition that enjoins what direction of mouse scrolling zooms in/out? (In other words, what considered forward/reverse zooming?)

Answer 1

Scrolling the surface of the mousewheel away from you - traditional upscroll [as opposed to 'natural'] is used as zoom in for all apps I've ever used that have that capability.

Presumably [though I never use it] if a user has natural scroll enabled, they will expect [& get] the opposite.

Answer 2

Wikipedia Scroll wheel:

Most often, rolling the upper side of the wheel away from your body is to scroll "upward" or "forward", and the reverse direction is to scroll "downward" or "backward".

In a graphical user interface, the "upward" motion moves contents of the window downward (and the scrollbar thumb, if present, upward), and vice versa. In other configurations (sometimes called "natural scrolling") the effect is inverted.
[...]
The scroll wheel was popularized by the Microsoft IntelliMouse in 1996 along with support for the mouse wheel in Microsoft Office 97.

The zoom in/out operation by the scroll wheel of Microsoft Windows was copied by all other computer manufacturers and so became the de facto standard.

Nevertheless, sometimes (rarely) I come across a program where the action of the scroll wheel is the opposite of what I'm used too, and that is really annoying.