Material Manager, what is the indicator in the corner?

[MelodyJane]

In the corner of each tile in the Material Manager, there's a little white bar that turns orange when selected, but also when you select one, a particular group of others show the white bar. It happens when a material is a copy of another, but also when the the materials are unrelated, or at least as far as I can tell. I googled around, but haven't found the answer. Does anyone know?
Also wondering, is there a way to know which materials are Redshift and which aren't, short of applying them and seeing if they work? Thank you!

[masterzone]

Dear MelodyJane, little bar you see on the material icon is dedicated to physical material, take a look to the Maxon's help picture below.

[MelodyJane]

Wow, I'm glad I asked, that's good to know! Thank you, Masterzone!