What's so special about 2,8,9,15,56,72 error codes?

[Nikita Kretov]

I'm doing little research about what metrics and formulas used to 
calculate SLA for kafka clusters. I found that some of major cloud 
providers offer managed kafka solutions. for example - aws msk (Amazon 
Managed Streaming for Apache Kafka)

Interestingly, aws msk SLA document defines ``Error``` as ```...any 
Apache Kafka API Request that returns the 2, 8, 9, 15, 56, 72 error 
codes, or an Apache Kafka API Request that upon retry returns the 19 and 
20 error codes as described in the Apache Kafka site...``` (from 
https://aws.amazon.com/msk/sla/ )
So my question is - Does someone know what's so special about this 
specific error codes ?

Thank you.