@xgranade @mcc have you read the Common Lisp spec? 
To be fair, the spec is very good, but they are also very explicity not giving any special significance to 8-bit bytes. And this is in paid of the spec being written decades after 8-bit bytes being standard.
https://www.lispworks.com/documentation/HyperSpec/Body/f_ldb.htm#ldb
www.lispworks.comCLHS: Accessor LDB