When I’m working on a website, I’ll format the copy so it’s easy for the client, designer and coder to understand and use the content. I’ll signpost the page title and meta description, and also point out which elements are graphics and links.
I’ll provide guidance on which headers should be H1 tags, which should be H2 (and so on). And obviously if I want copy to be bold on the page I’ll bold it in the deck. If there’s a form on the page, I’ll detail the type of fields I think should be used, such as drop downs for state, and check boxes for privacy agreement. I also make it very clear to the client what will (and will not) be seen on the page by greying out all the geeky tech instructions.