"Auto-extinguishing quality grade 1"

[MsNomer]

Is this good or bad for flammability of a foam underlayment?

Also: "smoke content 20 SDR
And: "oxygen index 27 Ol

[Roly]

As I understand the oxygen index is how much oxygen is needed to support continuous combustion.    Normal atmosphere is about 20.9% , the 27 means it will need more oxygen (27 %) to support continuous combustion.   So it will not continue to burn on its own in a normal atmosphere.     I do not know about the smoke rating.     Roly

[Cooler]

Also note that some products labeled as "self-extinguishing" are only so if used in the horizontal position.  When used in walls they may not be self-extinguishing.  

There are separate standard for walls and floors/ceilings.