File type overview
You can open and save InCopy documents as several different file types.
Assignment files (.inca) These files are a subset of the InDesign document. They display content and styles, as well as page geometry from the parent InDesign file. Assignment files can display different levels of visual fidelity (wireframe, assigned spreads, or all spreads). The InDesign user sets these options before creating the assignment file. Only InDesign users can create assignment files; only InCopy users can open assignment files.
InCopy CS2 content files (.incx) This is the default file type when exporting stories or graphics from InDesign, and when saving or creating new documents using InCopy. When opened as stand-alone files, these files display content and styles, but no page geometry (layout information from an InDesign document). This file type appears as InCopy Interchange in the Save As dialog box.
Template files (.inct) Templates are useful starting points for stand-alone documents, because you can preset them with page size dimensions, text area dimensions, styles (paragraph and character), XML tags, swatches, pretagged sample content, and so on. Template files open as “Untitled” documents and display content and styles, but no page geometry (layout information from an InDesign document). This file type appears as InCopy Interchange Template in the Save As dialog box.
InDesign files (.indd) These files provide full fidelity of the InDesign document, including content, styles, and layout of all page items. InCopy users can edit only those content items made available to them by InDesign users. Other items can be viewed in full fidelity, but not edited.
InCopy CS files (.incd) To open InCopy CS2 documents in InCopy CS, you must save them in .incd format, the file format used by the InCopy CS application. Be aware that content created by new functionality in InCopy CS2 may be modified or omitted when you open the file in InCopy CS. For example, graphics (a new feature of InCopy CS2) will drop out. This file type appears as InCopy CS Document in the Save As dialog box.