Hello,
What are the meaning of the different colors of groups and components in the outliner? especially the color RED?

thank you,

Hello,
a friend helped me with building a house model, but he didn't name the shapes and groups and components, and when I received the file I found out that his groups are not very accurate.

after renaming them, I still have 3 items in the outliner:
1- a line: how do I know to which shape?
2 & 3 - show on the outliner but when I choose them nothing is displayed on the screen

thank you,