We describe the NIF approach towards representing annotations and focus on roundtripping: the conversion of existing digital content from formats like Word, HTML etc. into NIF and re-integration of annotations into the original file format. Such roundtripping is needed for many industry applications of linguistic linked data and natural language processing. Roundtripping is not always possible and constrained by 1) possibilities to store annotations in the original format, while preserving existing information (e.g. HTML inline tags) and 2) constraints of the annotation model, which is basicaly tree-structured for markup languages like generic XML or HTML. There is no general solution to this problem. Developers of roundtripping applications should use existing libraries as much as possible and leverage them to their needs.