Hi Michael,

It seems we've got different interpretations and experiences in what we think a traditional layer system is.
Unigraphics (NX) was first developed in the '70's so there was no influence from Autocad which came out in the '80's.
Mechanical cad systems that I've worked with have always been 256 layers, some called them levels. I'll explain how NX handles object organisation, in a single 3d space and history free, parametric modelling and using sub assemblies within assemblies is also used for object organisation but that's a different story.

Layers in NX is just a container for an object or objects, it does not control the object attributes, like colour, line thickness, etc. all you can do with a layer is control the object interactive/visual state on the screen, like; Work(active), Selectable, Visible Only, Invisible.
Colours and the other object attributes are per object and controlled separately with the object preferences window, so you can have as many objects with different attributes for each, under one layer.

The basic layer window, layers on the right and what categories those layers are in on the left, note layer 62 is in 2 different categories.
when you right click on a layer you get the visual options.



Then when you tick the box that says 'Category Display' you get the categories in a hierarchy tree showing layers are under each category.



To change the object attributes for the work (active) layer you bring up the 'Object Preferences' window (left picture), to edit object attributes you right click on the object and pick 'edit object display' and that will bring up the 'edit object' window (right picture).




Once you've assigned layers and attributes to an object, it's a matter of using the layers, the filter system and hide/show to manage you work.

This is the filter system, which you can filter objects by types, colours, layers, etc.



'Type' selection filter.



'Colour' selection filter.


That's it in a nutshell. It would be easier and clearer if I actually showed the system on screen in action.

Any questions, feel free.

Cheers