Glossary
Every term used across the zetl guide, in one alphabetised list. Entries link to the primary page where the concept is explained in depth.
A
AST — Abstract syntax tree. zetl uses a canonical schema (zetl-ext AST v1) that every render-pipeline stage receives and returns. Inspect with zetl ast sample. See Render Pipeline Hooks.
B
Backlink — An inbound wikilink. If page A contains [[B]], then B has a backlink from A. Surface with zetl backlinks. See Backlinks.
BLAKE3 — The cryptographic hash zetl uses for content-addressable blocks and the Merkle leaves that feed the incremental cache. Fast, parallelisable, keyed. See Blocks.
Block — A content-addressable unit within a page: a heading, paragraph, code fence, table, blockquote, list, SPL block, or frontmatter. Each block has a BLAKE3 hash. See Blocks.
C
Capability URL — A sharing link with an embedded fragment secret (#k=…) that decrypts a static-built vault client-side. No server required. See Capability URLs.
CRDT — Conflict-free replicated data type. zetl uses Peritext for real-time co-editing so two authors can type into the same paragraph without conflicts or last-writer-wins. See Co-editing.
D
Dead link — A wikilink that points at a nonexistent page. zetl check --dead-links lists them. See Finding Orphans and Dead Links.
Defeasible logic — A logic where conclusions can be revoked when stronger evidence arrives: “birds fly; penguins don’t; Tweety is a penguin” correctly concludes Tweety doesn’t fly. zetl’s optional reasoning layer is built on this. See What is Defeasible Reasoning.
E
Ecosystem — An external render toolchain zetl can plug into: Pandoc, mdBook, or remark. Each is a set of render-pipeline adapters gated behind a cargo feature flag (ecosystem-pandoc, ecosystem-mdbook, ecosystem-remark). See Plugin Ecosystems.
F
Forward link — An outbound wikilink. If page A contains [[B]], A has a forward link to B. Surface with zetl links. See Following Links.
Frontmatter — YAML metadata fenced between --- lines at the top of a page. zetl reads a handful of reserved keys (title, tags, parser, description) and passes the rest through to templates. See Frontmatter Fields.
H
Hook — An executable zetl invokes at a lifecycle point (pre-build, post-build, on-save) or inside the render pipeline (pre-parse, transform, post-render). Hooks live under .zetl/hooks/ in the vault or hooks/ in a theme. See Lifecycle Hooks, Render Pipeline Hooks.
J
jj (Jujutsu) — The VCS engine that backs zetl’s silent snapshots when --features history is enabled. Commits happen in .zetl/jj/ without touching your git repo. See Snapshots Under the Hood.
M
MCP — Model Context Protocol. A standard for exposing structured tool access to LLM agents. zetl mcp serves the vault as an MCP endpoint. See MCP Server.
Merkle tree — A hash tree over vault blocks. Changing one paragraph only invalidates the hashes along its root-path, so zetl’s cache reparses just that page and its consumers. See Blocks.
O
Orphan — A page with no inbound and no outbound wikilinks. Either write one, link to it, or delete it. See Finding Orphans and Dead Links.
P
Passkey — A WebAuthn credential — Touch ID, Windows Hello, a hardware key like a YubiKey. zetl’s multi-user mode uses passkeys so there are no passwords in the vault. See Passkeys and Accounts.
S
SimHash — A locality-sensitive hash that produces similar bit-strings for similar inputs. zetl similar uses it to find title matches within a Hamming-distance threshold. See Similar Pages.
Slug — The URL-safe version of a page title, used in paths on the built site. Zettelkasten Method.md becomes the slug zettelkasten-method.
SPA shell — Single-page-application navigation shell used by the web server and built site. Same-origin clicks swap only the <main data-zetl-volatile> region, keeping the sidebar and graph widget mounted. Opt in via [spa] enabled = true in theme.toml. See Customising the Look.
SPL (Spindle Lisp) — The defeasible-logic language zetl uses for vault rules under --features reason. Rules live in fenced code blocks (```spl) inside your pages; the reasoner consumes them globally. See Writing SPL.
T
Transclusion — Embedding part of one page inside another. The syntax is ![[Page]] to embed a whole page, ![[Page#Heading]] for a section, or ![[Page^block-id]] for a specific block. See Embeds and Transclusion.
V
Vault — Any directory zetl operates on. No registration, no config file required. A vault becomes zetl-aware the first time zetl index runs against it and the .zetl/ cache directory appears. See Vaults.
W
WebAuthn — The W3C standard for passkey authentication. zetl’s multi-user mode is a WebAuthn relying-party. See Passkeys and Accounts.
Wikilink — A [[Page Name]] reference. The foundational link syntax zetl is built around. Variants: [[Page|Alias]], [[Page#Heading]], [[Page^block-id]], ![[Page]] (transclusion). See Wikilinks.