sqlnet.allowed_logon_version_server

Initial reading for upgrade from 12.1.0.2 SE-2 to "18c".  In the Database Upgrade Guide, several pages are given to dealing with older, case-INsensitive passwords.  I've been planning on addressing that issue before the upgrade, as we are still running with SEC_CASE_SENSITIVE_LOGON=FALSE on a couple of our databases.  I know that that init parm is deprecated, but I was surprised to see that it is deprecated "in favor of setting sqlnet.allowed_logon_version_server".   (Net Administrator's Reference).  It has alwasys been my understanding that the sqlnet.ora, tnsnames.ora, and listener.ora files were only used by the respective tns components - sqlnet.ora and tnsnames.ora by the client, and sqlnet.ora and listener.ora by the listener - not by the database itself.  But here it sounds like the database instance itself reads sqlnet.ora and uses it (or at least certain entries) as a supplement to the init<sid>.ora / spfile.