Ligatures are two letters that are either fused together to form a different character, or they are two letters that are placed closely together (undercut). As a rule, only two letters in the same morpheme are printed as ligatures in German texts.

Both the consonant ligatures (tz, ct, ts, ff etc.) and the ligature ij as well as the ligatures common in German-language texts such as fi, fl, ft, their derivatives, as well as fk, fj, fh, fb, fz, ll, mm, nn, st, ch, ck, ct, th, tt, tz, kk, Qu, ΕΏi, ΕΏΕΏ, ο¬…, ΕΏch can be transcribed differently on the three levels of the Ground Truth.