Proposer Window

Just sending this message to check my understanding regards to the below on P-Chain proposer nodes;

Node Proposer: NodeID-111111111111111111116DBWJs

Message: This is an empty node id returned by avalanche go as a constant. This is an indicator of a block that is proposed by somebody outside of the proposer window. This is not an actual validator

I assume the proposer window means that the snowball algorithm sample (assume sample size 20 and quorum size 14 - I am not sure about that it’s just how I remember reading about it) could not reach a consensus and then assuming again, the algorithm goes the multi-color problem loop and ends up with a proposer were not in the sample of nodes as a proposer.

Like to learn more about it, thanks very much in advance to whoever takes the time to respond.