When you specify the
AUTHID= option, every table that is referenced by the libref is qualified
as
authid.tablename before
any SQL code is passed to the DBMS. If you do not specify a value
for AUTHID=, the table name is not qualified before it is passed to
the DBMS. After the DBMS receives the table name, it automatically
qualifies it with your user ID. You can override the LIBNAME AUTHID=
option by using the AUTHID= data set option. This option is not validated
until you access a table.