groups. explain them to me.

[My_Key]

hello to all
Everywhere, I use vw and something I learned, but the groups remain a mystery. In the sense, I know what they are and I use them often, even in other cads, but I have a problem: If I have lines that are in one class and the group, I have seen that the lines can remain in that class but the group can be married in another class!! I mean, I have the content on one side and the container can be on another, I don't know if I explain.
I have done a test now, with lines in the walls class, the groups, and the group turns out to be in the none class instead of in walls, as it seems logical must be.
I don't understand the usefulness of this.. is there a way to avoid this, or a way to reason in making the groupings that help me not to make confusion?
Thank you

 

[My_Key]

place also two screenshots of the problem. the situation is a little different, in the sense that here is the layer to be different, but the concept is the same I believe.
Thank you

 

[lory.b]

Hi.
grouping design elements often is useful. Maybe I want to isolate them, or move everyone together without risking losing one, etc.
practical example. I have a tower of 16 floors (3d) covered with glass modules 80x390. for each facade I have created groups of these modules so that I can edit, move, delete or replace them, without risking to hook some other element of the model, which is quite complex.
in the 2d drawings, on the other hand, often group of the elements of a plant, for example, to copy and paste them on the next plant.... the examples of use of the groups are quite vast.
the group obviously belongs to the class at that active moment in which you create it. as for symbols.
the existence of a group makes sense as long as it serves. then it is good to cheat. especially if you export to dwg. and you will notice that each element returns to its class.
as for any other design elements, even for the group it is good to be aware of the class in which you are creating it.
I do.

 

[My_Key]

the group obviously belongs to the class at that active moment in which you create it. as for symbols.

That's what I missed.
Thank you