Yesterday I was browsing a PDF issue of the German magazine “Stern” on the train and I noticed a lot of peculiar, prominent typos:

“Tecāik” instead of “Technik”, “Soā” instead of “Sohn”, etc. Is this some kind of font encoding mishap? Oddly enough, when copying and pasting affected text blocks, the letters would come out correct.

The train had an unscheduled stop in the middle of nowhere, and I began investigating a bit. My best guess was that this is related to an ancient InDesign bug where certain letter combinations would falsely be treated as ligatures with a seemingly random replacement glyph (in this case, inserting “ā” as a ligature for “hn”). This would explain how the copied text remains intact.

• Weird ligature issues (Feb 2011)
• InDesign false ligatures bug (Jun 2018)
• Variable data problem (Sep 2020)

Here comes the kicker: This wasn’t just an issue with the PDF version! I bought a physical copy of the magazine today, and it seems these typos are all over the print edition as well! That’s a lot of misprints, Stern has a circulation of about 250,000 copies.

Makes you wonder how a mistake like this can happen without anyone noticing… There are at least 30 instances of this throughout the issue!

Bonus guessing: When looking at the codepoints of the contracted letters, we see that they are close to letter pairs that do have a proper ligature. “fi” and “fl” usually have ligatures, and if we modify each letter by +2, we end up at “hk” and “hn”.

Letters	ASCII	Ligature
f i	66 69	U+FB01 = fi
f l	66 6c	U+FB02 = fl
h k	68 6b	U+0100 = Ā (incorrect)
h n	68 6e	U+0101 = ā (incorrect)

Coincidence? I think… maybe! :)