Earlier quoted context omitted.
> separating data from instructions There's been a lot of talk about this (for years, honestly), but it all stems from a fundamental nonunderstanding of how LLMs work. There is no distinction for an LLM; "instructions" are a prompt concept, nothing more. It's not possible to separate the two, because LLMs simply take text (ie your instructions, then the data, or maybe in a different order, or maybe something complete…
You can't guarantee an LLM does anything. Custom data can often subvert the machine whether or not it's instructions. But that doesn't mean that separation between instructions and data is impossible. You can format them in different ways, and you can prevent the output tokens from ever using instruction formatting.
Even if special tokens are used absolutely perfectly (somehow avoiding escapes or ambiguities or reflected attacks) they are ultimately the same as highlighting all the parts of the document in different colors. You've saved the signal, but there's no mind to receive the intended meaning.
This means that your markers--while far more exclusive--ultimately exist on the same data-level as punctuation and using ? to indicate a question.
> you can prevent the output tokens from ever using instruction formatting
The right words may still outweigh the formatting around them, the same way that they can already outweigh other words around them.