Indexing

Greetings all, Following some poor response times during recent tests of a new application, I've taken a look at the SQL generated and have a simple question for all you Informix gurus out there. If we have : (i) a composite index on a table defined on columns (A,B,C) (ii) a query filter reads "WHERE C=whatever AND B=whatever AND A=whatever" ... is Informix smart enough to realise that the index in (i) should be used ? Or is it best for the query to be coded in the precise order of the index definition ? I've executed some EXPLAINs which seem to suggest that Informix *is* smart enough, but I'm not entirely convinced by the output from this tool. Thanks in advance for your help. Regards, John