No, I mean all LEDs. The cathode marks are basically randomly assigned. This is because each company more or less designs one leadframe/package structure per s

No, I mean all LEDs. The cathode marks are basically randomly assigned. This is because each company more or less designs one leadframe/package structure per size or type of LED. Sounds reasonable, right? But LED dice aren't made of silicon. They're made of weirdo high-bandgap materials, and every color is different in its own way. From physics alone, some of the colors end up with cathodes on top of the dice and some of the colors end up with anodes on top. They all get bonded in to the package the same way. So... that marking built in to the package? That's always the "top of die" wire next to it. But "top of die" might be cathode, or it might be anode. Flip a freaking coin! If you want to see this clearly, find a datasheet that covers an entire series of LEDs. Vishay often does this, here's one: https://www.vishay.com/docs/82437/vlmo1300.pdf https://www.vishay.com/docs/82437/vlmo1300.pdf . They'll tell you the marking locations for each color individually. Notice how they're all completely different? Yeah. Could the manufacturers do better? Yes. Yes, they could. We all wish they would do better. But they do not. So LEDs are the stuff of nightmares for people who assemble boards. Through-hole parts are somewhat better (but there are certainly rogues!), but this is 2026: the volume's in surface mount. Multipin LEDs are no better. The SMD no-lead versions are again fairly randomly marked. The PLCC-4 types are usually "cutoff corner near pin 1", but I've seen it as pin 4... or pin 2... constant vigilance is the only solution. Constant vigilance!