Wow. That's basically what I've heard of as the the Kangxi radicals problem. From what I could gather from 5-minute search, the mechanism is: PDFs don't use Un

Wow. That's basically what I've heard of as the the Kangxi radicals problem. From what I could gather from 5-minute search, the mechanism is: PDFs don't use Unicode or ASCII codepoints, but Glyph ID used by fonts. Therefore all strings are converted to sequences of that Glyph ID. Original Unicode or ASCII texts are dropped, or can be linked and embedded for convenience. In many cases, a reverse conversion from ID to Unicode is silently done when text is copy-pasted or extracted from PDF. That silent automatic reverse conversion tend to pick the numerically smallest Unicode codepoint assigned to the glyph(letter shapes), and many fonts reuses close-enough glyphs for obscure Unicode characters like ancient Chinese dictionary header symbols and dozen Unicode siblings of hyphens. Unicode also tends to have those esoteric symbols higher up in the table than commonly used ones. Therefore, through conversion into Glyph ID and back into Unicode, some of simple characters like `角` or `-`, which glyphs tend to get reused to cover those technicalities, sometimes gets converted into those technicalities at remote ends. 1: https://en.wikipedia.org/wiki/Kangxi_radical https://en.wikipedia.org/wiki/Kangxi_radical 2: use TL: https://espresso3389.hatenablog.com/entry/20090526/1243327471 https://espresso3389.hatenablog.com/entry/20090526/124332747... 3: use TL: https://github.com/trueroad/tr-NTTtech05 https://github.com/trueroad/tr-NTTtech05 4: use TL: https://anti-rugby.blogspot.com/2020/08/Computer001.html https://anti-rugby.blogspot.com/2020/08/Computer001.html