What is this odd glyph?

[DS_7476678]

Can someone please tell me what this glyph/icon means when next to an assembly, in the model tree?
(see temp.png)
PTC website offers no help.

Thank you.😐

[DS_7476678]

In case the temp.png file does not load for you like it will not for me, the glyph in question is a red octagon with a white exclamation mark inside of it.

Thank you.

[BenLoosli]

My guess is that there is something wrong in that assembly. 

What do you see when you open that assembly?

[StephenW · Accepted solution]

https://www.ptc.com/en/support/article/CS58783?source=search

Red exclamation mark - feature failed or component is missing (introduced in Creo Parametric 3.0)

[DS_7476678]

Thank you, I seemingly could not find that article on my own!
That makes sense now along with what I've learned about these older, legacy models.

Yours and Ben's help is greatly appreciated.