Dear Patrick and Dominik,
I was thinking precisely of Einicke's Randausgleich when I wrote earlier. I'm relieved to read that you also haven't the impression that it's a word-divider, I was never convinced that it has this function too.
As to the terminology, I'm not really satisfied with line-filler and I think that hyphen is better - although in my perception as a non-native speaker, the two terms are synonymous, so I'm waiting for the jury of native speakers to decide.
Best wishes,
Camillo
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