# protostone

URL: https://blockspace.wiki/glossary/protostone/

An Alkanes message carried inside a runestone's OP_RETURN, in the protorunes field (tag 16383), which plain runes ignores. A protostone names a protocol tag, a pointer, a refund output and a cellpack, the call to a contract. One runestone can hold several, and a protostone can point at the next one through a "shadow" output number past the real outputs.

Sources:

- Blockspace Holdings records
- block.space docs: data types · https://block.space/docs/datatypes

Updated: 2026-10-20