ORA-65096: invalid common user or role name

sys@LUOCS12C> create user luocs identified by oracle default tablespace luocs;
create user luocs identified by oracle default tablespace luocs
            *
ERROR at line 1:
ORA-65096: invalid common user or role name

sys@LUOCS12C> !oerr ora 65096
65096, 00000, "invalid common user or role name"
// *Cause:  An attempt was made to create a common user or role with a name
//          that wass not valid for common users or roles.  In addition to 
//          the usual rules for user and role names, common user and role 
//          names must start with C## or c## and consist only of ASCII 
//          characters.
// *Action: Specify a valid common user or role name.
//
根据错误提示了解，在CDB中用户得以C##开头，如下：
sys@LUOCS12C> create user c##luocs identified by oracle default tablespace luocs;

User created.