An INX file is a document exported by Adobe InDesign in XML format. It contains information that completely describes an InDesign (.INDD) file, including pages, page content, text frames, colors, margins, guides, etc.

InDesign CS2 files exported in the INX format can be opened by InDesign CS. All page content and formatting is recognized by InDesign CS except for features that are only available in InDesign CS2. Some of these features include footnotes, SING glyphlets, tracked changes, anchored objects, imported PSD files with layers, and object styles. To export an InDesign document in the INX format, first choose File→Export. Then select InDesign Interchange from the Formats menu (Mac) or the File Type menu (Windows) and click Save.