Is it necessary to use structured framemaker to publish to the web?

I am not even sure if the client knows what " Publish to the web" means. He just wants to make sure he can in the future. Everything I read says you can just save to XML from FM 2015 and I seem to recall that it will do it from unstructured FM, but I haven't found where is says explicitly that it will do it from unstructured FM so that I can show him.

If this is true, then it will allow us to create his paper manuals in unstructured FM and then save them out to XML in the future to give to a web designer.

Also, if you can use unstructured FM to save to XML, is there a primer or guide to things to do or avoid to make the XML output smooth?

Thanks in advance

Chris