Non-digestable, complex and simple carbs differences.

Just trying to get my head around non digestable carbs. My understanding is that digestable carbs are either complex, as in flour or simple, as in sugar. These are often given as total carbs yyy of which xxx is sugar on the product labels.

However, some products which are said to be zero carb still have total carbs zzz on the label. Are these the category referred to as non digestable carbs, ie the type that pass through the body and which are not converted into glucose?