Hi lyes, the MoI one is designed to be flexible - the nice thing about it as compared to traditional layers is that you have several different methods that you can use in combination to organize your model, you are not only limited to just layers only.

For example with traditional layers it does not really work to have a method to show all curves in the model because there isn't any way to show an individual object by itself if the object's layer is hidden.

Similarly there isn't an easy way to show just a specific named object with just 1 click because to show an object with a traditional layer system means that the layer that the object is on must be set to be turned on, making any other things also on that layer also be turned on.

MoI's system allows you to do these different kinds of show/hide type tasks that a traditional layer system just does not allow.

Meanwhile if you want to use layers in MoI, the Styles section works very similar to them making a set of categories that controls object colors and also lets you hide and show all the objects belonging to that color slot.

This gains a lot of flexibility with having a single browser UI that allows for these various kinds of operations, like "show all curves", "select all solids", "show the object named Object1", "Lock all objects with Style=Red", ... That's a lot of flexibility and operations combined into one UI.

All the different browser item actions like Select, Hide, Show, Lock, Unlock, Isolate, make isolated selection, work across these different browser sections, so you gain the ability to do all these actions to specific named objects or object types and not only just to a layer.

- Michael