Hi Bill
That is correct. Changes saved as wpd format will be retained though. The issue when taking these between MSO and WPO is that they do some things differently than us architecturally, so some things are either very hard, change or are just impossible to support. The trade-off for this is that WPO works in a manner that makes sense to people versus ... ahem... other products.
My recommendation would be to save in WordPerfect format if you are using this with other WP users or just saving an interim doc. If you need to collaborate with others you can either highlight changes (the strikeout, highlight, etc tools transfer over so that will get your message across) or make a PDF of your changes to share back with them. If you make lots of text changes they can cut/paste from the PDF to simplify things for themselves.
Thanks
Jay