Need some info about "Clean pipe"

[sakthi vadivel <sakthivadivel.ccie () gmail com>]

Hi,

Is there any one has idea about what is "clean pipe" ? what exactly upstream
providers do using this term " clean pipe"?
whether would it add any latency in the traffic flow ?

Please if you have any link or draft , please share it.

Planning to implement it in our peering pipes ?

thanks and regards,
sakthi