Glossary
This glossary gives the short definitions used throughout the book. Entries for named standards link to their normative specification or the standard's official project documentation.
AT Protocol
AT Protocol, usually shortened to ATProto or atproto, is the federated protocol on which idiolect publishes records and services.
AT URI
An AT URI identifies an ATProto repository or record with an authority, an optional collection, and an optional record key. An AT URI is mutable unless paired with a CID.
Catalog
The catalog is the orchestrator's indexed store of typed idiolect records. Queries evaluate over this local read model; the catalog is not a global registry or an authority over the records it contains.
CID
A Content Identifier (CID) is a self-describing content address built from a cryptographic hash and format metadata. ATProto uses CIDs for links whose target bytes must be verifiable.
Complement
A complement stores source information that a lens cannot reconstruct from
its view alone. A put operation uses that information when it propagates an
edited view back to the source schema.
DID
A decentralized identifier (DID) is a URI that identifies an entity and resolves according to a DID method. ATProto accounts use DIDs as stable account identifiers even when handles or hosting providers change.
Dialect
A dialect is a community's published bundle of preferred schemas, lenses, and deprecations. It records a collective convention without making that convention global.
DPoP
Demonstrating Proof of Possession (DPoP) binds an OAuth token to a client-held key. The ATProto OAuth profile requires DPoP with server-issued nonces.
Encounter
An encounter is a signed record of one lens invocation, including the lens, the source and target schemas, the purpose, and the observed outcome.
Firehose
An ATProto firehose is the repository event stream described by the ATProto synchronization specification. PDSs emit events for hosted accounts; relays may aggregate many upstream streams.
Idiolect
An idiolect is one party's choice of schemas, lenses, vocabularies, and conventions. The term names the local unit of variation that idiolect preserves.
Language
A language, in this book's three-level model, is the federated substrate on which idiolects and dialects interact. It does not denote one centrally managed schema catalog.
Lens
A lens is a bidirectional translation between a source schema and a target
schema. Its get operation produces a target view; its put operation
propagates edits to that view back to the source, subject to stated lens laws.
Lexicon
Lexicon is ATProto's schema language for records, XRPC endpoints, and event-stream messages. Each Lexicon file is named by an NSID.
Lexicon family
A Lexicon family, also called a record family in generated APIs, is the set of related Lexicon records emitted and versioned together under one namespace policy.
NSID
A Namespaced Identifier (NSID) is a global
semantic identifier whose authority appears in reverse-domain order, followed by
a final name segment. dev.idiolect.belief is an NSID.
Observation
An observation is a signed aggregate computed from a stated scope of encounters by a named observer method. It is evidence produced by a method, not the raw trace of a single translation.
Observer
An observer consumes encounter or record data, applies a declared method, and publishes observations. The method and its inputs remain inspectable so consumers can evaluate the result.
Open enum
An open enum accepts a known set of values while preserving unknown strings. This representation lets older consumers retain values added by later producers.
OAuth
OAuth is the authorization framework ATProto clients use to obtain scoped access to PDS resources. The ATProto profile combines OAuth with PKCE, PAR, and DPoP requirements.
Panproto
Panproto supplies the schema graphs, protocols, protolenses, lens runtime, compatibility checks, and parsing machinery that idiolect uses. This book targets Panproto 0.71.0.
PDS
A Personal Data Server (PDS) hosts ATProto accounts, repositories, authentication, and blobs. An account may migrate between PDS providers without changing its DID.
Protocol
A protocol, in Panproto's formal model, supplies operations and laws against which schemas and lenses can be interpreted. This use is narrower than “network protocol.”
Protolens
A protolens is Panproto's schema-level description of a bidirectional transformation before that description is instantiated as a runtime lens.
Recommendation
A recommendation is a community's signed endorsement of particular schemas or lenses, optionally conditioned on verifications. It records social authority and does not itself prove a mechanical property.
Record
An ATProto record is a typed data object stored in an account repository. Its
$type value names the governing Lexicon schema, and its collection is normally
the same NSID.
Repository
An ATProto repository is an account's signed, content-addressed collection of records. A PDS stores the repository and distributes its commits through the ATProto synchronization protocol.
Schema
A schema describes the admissible structure of a record. Idiolect reads ATProto Lexicons into Panproto schema graphs for validation, comparison, and lens execution.
Strong reference
An ATProto strong reference pairs an AT URI with the target record's CID. The URI locates the record and the CID identifies the exact content.
Theory
A theory is a named collection of formal structure and constraints used to compose Panproto schemas. Idiolect's theory files state reusable semantic components rather than runtime records.
Verification
A verification is a signed report that a named runner checked a particular
property of a lens and obtained holds, falsified, or inconclusive.
Vocabulary
A vocabulary is a governed graph of concepts and relations that record fields may reference. Values remain ordinary identifiers; the vocabulary supplies their machine-readable relations and provenance.
XRPC
Lexicon RPC (XRPC) is ATProto's convention for HTTP query and procedure endpoints named by NSIDs.