What joins are available in Informix 9.2?
Ok, at least an outer join works just with different syntax: just using OUTER with a comma after the first table and a WHERE instead of an ON.

Edited to add an example from http://publib.boulder.ibm.com/infocenter/idshelp/v10/index.jsp?topic=/com.ibm.sqls.doc/sqls679.htm

SELECT c.customer_num, c.lname, o.order_num FROM customer c, 
   OUTER orders o WHERE c.customer_num = o.customer_num