I use linked XML to import content for my book into my InDesign document. It's one text flow across multiple pages, and certain content deserves to have its own frame (e.g., pull quotes, images, exercises, and captions).
I imagine I could get the correct pieces of text to flow into the correct frames with line breaks, but I don't want to manually insert line breaks after import. How can I include InDesign frame breaks into my XML document?
You don't insert frame breaks into the XML contents. You do that in Paragraph Styles→Keep Options, where you set the start of the paragraph in the next frame.
But it requires that your XML content be explicitly mapped to paragraph styles, either via Tags→Map Tags to Styles, which automatically applies styles to corresponding tags when content is placed onto the page, or by declaring aid:pstyle attributes on your XML nodes.
Lastly, that won't work straight away with pictures unless you specifically embed the img nodes inside a text node with a corresponding paragraph style.
