The MSSQL module provided by PHP is not available in 5.3+, so that DBAL needs to be removed since we require 5.3.2+. The documentation may need to be adjusted since it will no longer be possible to connect to MSSQL 2000 directly, only through ODBC. The SQLSRV driver (mssqlnative dbal) only supports MSSQL 2005 and higher.