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9 · How the spec evolves (ZEPs) ​

Status: stub.

A ZEP is a Zarr Enhancement Proposal: the mechanism by which the specification changes. This chapter demystifies the acronym and the process.

What this chapter will cover ​

  • What a ZEP is and the problem it solves: changing a shared spec without breaking everyone.
  • The lifecycle: draft → discussion → acceptance, and who accepts it. As of ZEP0011 (accepted 2026-05-29), specification ZEPs are overseen and accepted by the new Spec Committee, not by the Zarr Steering Council. This replaced the earlier mechanism of unanimous ZSC approval plus majority approval from the now-dissolved Zarr Implementation Council (ZIC).
  • The distinction between a ZEP that changes the specification (a Spec Committee matter) and one that changes project governance (a ZSC matter). Keep these separate; they travel through different bodies.
  • A worked example of a real ZEP and what it changed. ZEP0011 is a good, recent one to read — it is itself a governance ZEP that reshaped who runs this very process.
  • How a ZEP relates to (but is distinct from) a convention or an implementation feature.

Who are these bodies?

This chapter only needs you to know that a body accepts ZEPs. For what the Spec Committee, the ZSC, and the affiliated projects actually are, and how ZEP0011's three-tier structure fits together, see Who steers Zarr.