“…Previous work has used sentence tags to convey domain (Kobus et al, 2017;Britz et al, 2017), speaker gender (Vanmassenhove et al, 2018), or target language formality (Sennrich et al, 2016a;Feely et al, 2019). Multiple tags can be used throughout source and target sentences, for example indicating linguistic features (Sennrich & Haddow, 2016;García-Martínez et al, 2016;Aharoni & Goldberg, 2017;Saunders et al, 2018) or custom terminology use (Dinu et al, 2019;Michon et al, 2020). Tags are usually incorporated throughout training, implicitly requiring the availability of reliable tags for large training datasets, although new tags can also be introduced during model adaptation .…”