gstat -h localhost:c:/db/ТипаФайл.fdb
  Database "c:\db\30\РеальноФайл.fdb"
  Gstat execution time Wed Apr 17 17:15:06 2019
  Database header page information:
        Flags                   0
        Generation              7
        System Change Number    0
        Page size               8192
        ODS version             12.0

databases.conf:
  c:/db/ТипаФайл.fdb = c:/db/30/РеальноФайл.fdb

  DefaultDbCachePages = 25K        # pages
  FileSystemCacheThreshold = 251K  # pages
  TempCacheLimit = 320M
  LockMemSize = 8M
  LockHashSlots = 40099
  ServerMode = Super
  RemoteServicePort = 3050
  ServerMode = Super

employee = $(dir_sampleDb)/employee.fdb
EmployEE = $(dir_sampleDb)/employee.fdb
{
  DefaultDbCachePages = 5K
}
security.db = $(dir_secDb)/security3.fdb
{
  RemoteAccess = false
  DefaultDbCachePages = 500
}

SQL> -- lowercase
SQL> connect 'localhost:employee';
Server version:
LI-V3.0.4.33054 Firebird 3.0
LI-V3.0.4.33054 Firebird 3.0/tcp (vm-centos-6)/P15:C
LI-V3.0.4.33054 Firebird 3.0/tcp (vm-centos-6)/P15:C
Database: 'localhost:employee', User: SYSDBA
SQL> select 'database' "Field", mon$database_name "Value" from mon$database
CON> union all
CON> select 'alias', mon$attachment_name from mon$attachments where mon$attachment_id = current_connection
CON> union all
CON> select 'page cache', mon$page_buffers from mon$database;

Field      Value                                                                                                                                                                                                                                                        
========== ===============================================================================
database   /opt/firebird/examples/empbuild/employee.fdb                                                                                                                                                                                                                 
alias      employee                                                                                                                                                                                                                                                     
page cache 5120                                                                                                                                                                                                                                                         

SQL> commit;
SQL> -- Mixed Case
SQL> connect 'localhost:EmployEE';
Server version:
LI-V3.0.4.33054 Firebird 3.0
LI-V3.0.4.33054 Firebird 3.0/tcp (vm-centos-6)/P15:C
LI-V3.0.4.33054 Firebird 3.0/tcp (vm-centos-6)/P15:C
Database: 'localhost:EmployEE', User: SYSDBA
SQL> select 'database' "Field", mon$database_name "Value" from mon$database
CON> union all
CON> select 'alias', mon$attachment_name from mon$attachments where mon$attachment_id = current_connection
CON> union all
CON> select 'page cache', mon$page_buffers from mon$database;

Field      Value                                                                                                                                                                                                                                                        
========== ===============================================================================
database   /opt/firebird/examples/empbuild/employee.fdb                                                                                                                                                                                                                 
alias      EmployEE                                                                                                                                                                                                                                                     
page cache 5120                                                                                                                                                                                                                                                         

SQL> commit;
SQL> -- UPPERCASE
SQL> connect 'localhost:EMPLOYEE';
Statement failed, SQLSTATE = 08001
I/O error during "open" operation for file "EMPLOYEE"
-Error while trying to open file
-No such file or directory
SQL>

SQL> connect 'localhost:employee'; commit;
Server version:
LI-V3.0.5.33180 Firebird 3.0
LI-V3.0.5.33180 Firebird 3.0/tcp (vm-centos-6)/P15:C
LI-V3.0.5.33180 Firebird 3.0/tcp (vm-centos-6)/P15:C
Database: 'localhost:employee', User: SYSDBA

SQL> connect 'localhost:EmployEE'; commit;
Server version:
LI-V3.0.5.33180 Firebird 3.0
LI-V3.0.5.33180 Firebird 3.0/tcp (vm-centos-6)/P15:C
LI-V3.0.5.33180 Firebird 3.0/tcp (vm-centos-6)/P15:C
Database: 'localhost:EmployEE', User: SYSDBA

SQL> connect 'localhost:EMPLOYEE'; commit;
Statement failed, SQLSTATE = 08001
I/O error during "open" operation for file "EMPLOYEE"
-Error while trying to open file
-No such file or directory