Spotlighting & Data Marking(SDM)

A family of low-cost transformations that make untrusted external text reliably distinguishable from trusted instructions. Delimiting wraps external content in unique boundaries, datamarking interleaves a special token through every whitespace of the untrusted span, and encoding such as base64 further separates it from the instruction channel. It is a cheap first line of defense against indirect prompt injection but degrades under adaptive attack, so it should be paired with layered defenses.