Finding the value for $INFORMIXSERVER

Is there a reliable way of identifying the value of INFORMIXSERVER for a given Informix installation. We often have to tell our customers how to find this value when they're installing our ODBC driver. I usally suggest they: a) Advise them to ask their dba b) Suggest they log in to Unix, run e.g. dbaccess to see their db, exit and then run 'env'. Sometimes the above are not possible. I have from time to time hacked round a few files under the Informix home directory, but was wondering if there was a more reliable way Thanks Allan