Fingers In Gymnastics

Ideally, what are the fingers to be in gymnastics, is it simply middle finger and thumb tucked in? Also, what's a good way to teach it to kids, I've heard some people say "pretend you're holding a marshmallow" but I think there must be a better way for kids to understand it than that.

What do you mean by this question? Fingers in which situation?

Generally, we want extended fingers together. I should go dig out my men's presentation video but I don't remember thumb tucked in or not.

Oh, I guess because I work with mostly girls. Boys do different right? Well I'm curious anyway of how girls are supposed to do it. Geez, I can't find a good picture, but basically like this

I guess I'm just wondering proper position, because ballet teaches something very specific for fingers, so for gymnastics girls is it just middle finger and thumb tucked in? Also, when is finger position used, basically just with certain poses such as arabesque? Sorry if I'm sounding obsessive-compulsive, I just like to understand the details of things.

Poses such as balance elements, beginning of tumbling passes and corner transitions and vault.