Oracle 12c - Study PDB$SEED
“_ORACLE_SCRIPT”=TRUE PARAMETER Should not be Invoked by Users (Doc ID 2378735.1)
Per Development, setting _ORACLE_SCRIPT to TRUE is something to be used only by Oracle internally. There may be a case where a note says to use it explicitly, but you should not use it outside the context of that note. In general is not to be set explicitly by users.
Have a good day! 2018/04 via LinHong