PS This has also been posted as a reply to the thread "OpenOffice Data Source Informix"

......

I think I now know the order - although I still can't get a connection to work. I assume that I have to:

1) Use the unixODBC utilities to register the ODBC drivers set up on the system (we use GNOME so did not have the ODBCConfig utility loaded).
1) Set up the driver entries in /etc/odbcinst.ini (manually edited via vi)
2) Set up the DSN's and connection parameters in /etc/odbc.ini (manually edited via vi)

I took the Informix default odbcinst.ini and odbc.ini and pasted them into the equivalent files in /etc. The problem that I did not spot at first here, was that Informix had comment lines beginning with a semi colon. Once that was removed, the Data Sources then appeard in the OO URL link.
I have tried using the unixODBC utilities isql, DataManager and odbctest, but cannot get a connection from any of them. From OpenOffice I get (Via Calc) an error:

No connection could be established for the URL sdbcdbc:Infdrv33.
With an sql error of:
SQL Status: 00000

I did think that the problem may then have been caused by my having turned off the 'rlogin,rexec and rsh' services on my server (for security). But I turned the services back on again today and retried the test with the same results.

Am I going down the right track?

I am used to specifying the protocol and service number (ie TCP port) when making Informix connections - but couldn't see these entries anywhere in the Informix ODBC ini files....