Vu meter of ssl mixer channels get red... But not in master....why? I'm still without understand....:(

[Jowe79]

Hi guys.... I can see... Which in some Mixer channel's in it's meters they get in red... But in master out NOT... Why? Are clipping mixing ssl channels? What means the red really in fader channels? Is rms value? With what measure i must take a eye? In peak mode in master fader then???
Thanks....

[Electric-Metal]