entity relationship diagram tool

I have a client that is interested in doing entity/relationship diagrams from an Informix database. They do not want to do case. They do not want to do re-engineering. They do not want to do application generation. They want a tool that will, at most, read database definition sql and generate e/r diagrams. And at the least, a drawing tool that will help with this process. If anyone knows of such a tool, I would welcome any information. Thanks dougmc@informix.com