upgrading a database whilst moving it

Running Informix OnLine 5.0. The Informix commands dbschema, dbexport and dbimport create an ASCII image of the schema and data associated with a specified database. dbexport produces a subdirectory consisting of the schema of the database plus the data files. As far as I can tell, dbexport provides a schema, <database>.sql as dbschema does but with additional 'links' to the ASCII data files of the actual database. When we reinstall the database onto a new platform with we wish to add some fields or tables to the schema. In this way we will have created a backwards compatible superset of the original data which we can then 'massage' into shape. Ha. So we want a copy of the data on the new machine, but under a new schema with some new fields or tables added. If it *is* do you have to alter the data files to reflect the addition of the new fields/tables or will dbimport allow creation of the fields with null value without changing the data? Would we have to hack the data files to represent the schema changes? This procedure is time critical, the shorter the time taken the better. Would this be the most efficient way of copying the database including the changes? Has anyone done this procedure? Is it possible? Any comments or suggestions on this procedure would be welcome. Rich.