This isn't the first time Anthropic has issued a watermark, but the latest iteration will apply to Mythos 5, Opus 4.7, Opus 4.6, and Sonnet 4.6.
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🤨 From Tuesday, older Claude models also hide a mark in what they write Anthropic emailed customers: on November 3 it starts watermarking text from Claude Mythos 5, Opus 4.7, Opus 4.6 and Sonnet 4.6. Newer models like Opus 5.5 already carry the same mark. You can't see it. It's a pattern in word choice, with no hidden characters. It travels with copy-paste and may survive some editing. Anthropic says it holds nothing about you, your company or your chats. It applies worldwide, not only in the EU, whose AI Act made it necessary. For now only regulators, police, media, fact-checkers and researchers can check for it. A hit isn't proof Claude wrote the text. Anthropic's help page says text Claude only proofread or translated can carry the mark too. @aipost 🏴
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