The DEFAULT Connection Specification

Instead of specifying an explicit database environment, you can use the DEFAULT keyword to request a default connection to a default database server. The default database server can be local or remote. To designate the default database server, set its name in the INFORMIXSERVER environment variable. This option of CONNECT does not open a database.

If the CONNECT TO DEFAULT statement succeeds, you must use the DATABASE statement or the CREATE DATABASE statement to open or create a database in the default database environment.