English: Mandatory ligatures in German blackletter type-setting. The examples read “Buchdruckerkunst” (art of book printing), “Setzkasten” (type case), and “Maß” (measure). Note how some ligatures are maintained, even in “Sperrsatz” (spaced setting). They are ch, ck, tz and sz (=ß). This image was set in Kleist-Fraktur.