Field Reference ◈︎

v0.5.6 · Current version

AIOSchema Field Reference Guide

Version 0.5.6

Document ID: as-doc-ref-field-v0.5.6 Status: Final Authored: May 2026 Published: June 2026 Author: Ovidiu Ancuta Authority: https://aioschema.org License: CC-BY 4.0

This document is a field-by-field reference for AIOSchema v0.5.6 manifests. It is a companion to the specification, not a replacement. For normative requirements, consult the specification directly.

Manifest Structure

Every AIOSchema manifest is a JSON object with two top-level keys:

{
  "core":       { ... },   // required
  "extensions": { ... }    // optional
}

Core Block Fields

The Core Block is required and immutable once created. No Core Block field may be modified after core_fingerprint is computed without invalidating the manifest.

The five fields included in the core_fingerprint computation are marked [FP]. These are the mathematically sealed fields; changing any one of them invalidates the fingerprint and fails Level 1 verification.

`asset_id` [FP]

Property	Value
Type	String
Required	MUST
Format	UUID v7 (SHOULD) or UUID v4 (MAY)
Verification level	L1
If absent	Verification MUST fail
If malformed	Verification MUST fail

A universally unique identifier for this asset manifest. UUID v7 is preferred: it is time-ordered and sortable. UUID v4 is acceptable. No other formats are permitted in conforming implementations.

Example:

"asset_id": "019d0d52-1d18-7024-abe3-ba37ea4796ba"

`schema_version` [FP]

Property	Value
Type	String
Required	MUST
Accepted values	`"0.1"` `"0.2"` `"0.3"` `"0.3.1"` `"0.4"` `"0.5"` `"0.5.1"` `"0.5.5"` `"0.5.6"`
Verification level	L1
If absent	Verification MUST fail
If unknown value	Verification MUST fail with unsupported version error

Identifies which version of the AIOSchema specification this manifest conforms to. Verifiers MUST reject unknown versions with a clear error message identifying the unsupported version string.

Example:

"schema_version": "0.5.6"

`creation_timestamp` [FP]

Property	Value
Type	String
Required	MUST
Format	ISO 8601 UTC: `YYYY-MM-DDTHH:MM:SSZ`
Pattern	`^[0-9]{4}-[0-9]{2}-[0-9]{2}T[0-9]{2}:[0-9]{2}:[0-9]{2}Z$`
Verification level	L1
If absent	Verification MUST fail
If non-UTC (offset notation)	Verification MUST fail
If invalid format	Verification MUST fail

The timestamp at which the manifest was created. MUST be UTC; the trailing Z is required and enforced. Offset notation (e.g. +05:00) is explicitly rejected. Implementations MUST normalise to UTC before writing this field.

Example:

"creation_timestamp": "2026-03-22T14:55:00Z"

`hash_original` [FP]

Property	Value
Type	String or Array<String>
Required	MUST
Format	`<alg>-<hex>` : algorithm token, hex digest
Pattern (per entry)	`^(sha256\\|sha3-256)-[0-9a-f]{64}$\\|^sha384-[0-9a-f]{96}$`
Verification level	L1
If absent	Verification MUST fail
If malformed	Verification MUST fail
If unsupported algorithm	Skip with warning; fail only if no supported algorithm found

A cryptographic hash (or array of hashes) of the original binary asset bytes. The single-string form is the legacy format. The array form supports multiple algorithms for durability.

Single-hash example:

"hash_original": "sha256-e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"

Multi-hash example:

"hash_original": [
  "sha256-e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
  "sha384-38b060a751ac96384cd9327eb1b1e36a21fdb71114be07434c0cc7bf63f6e1da274edebfe76f65fbd51ad2f14898b95b"
]

Supported algorithms:

Token	Digest length (hex chars)	Status
`sha256`	64	REQUIRED
`sha3-256`	64	OPTIONAL
`sha384`	96	OPTIONAL

Multi-hash verification: if any supported algorithm matches, hard match succeeds. If all supported hashes are present but none match, hard match fails. If no supported algorithm is found in the array, verification MUST fail.

`creator_id` [FP]

Property	Value
Type	String
Required	MUST
Format	UUID v7/v4 (anonymous mode) or `ed25519-fp-<32hex>` (attributed mode)
Verification level	L1
If absent	Verification MUST fail
If malformed	Verification MUST fail

Identifies the creator of the manifest. Two modes are supported:

Mode	Format	Description
Anonymous	UUID v7 (SHOULD) or UUID v4 (MAY)	No identity disclosed. Auto-generated if not supplied.
Attributed	`ed25519-fp-<32hex>`	SHA-256 fingerprint of Ed25519 public key (first 128 bits = 32 hex chars). Persistent across all manifests signed with the same key.

Verifiers infer the mode from the value: ed25519-fp- prefix → attributed; valid UUID → anonymous.

creator_id is a permanent identity anchor. It does not change when keys rotate; keys are replaceable tools, creator_id is the identity. See signature for key usage.

Anonymous example:

"creator_id": "019d0d52-1d17-7062-bbf8-3bbaf172122c"

Attributed example:

"creator_id": "ed25519-fp-bac64206390ddefc552ade9038c1ae18"

`core_fingerprint`

Property	Value
Type	String
Required	MUST
Format	`sha256-<64hex>` (same pattern as hash_original)
Pattern	`^(sha256\\|sha3-256)-[0-9a-f]{64}$\\|^sha384-[0-9a-f]{96}$`
Verification level	L1
If absent	Verification MUST fail
If mismatch on recomputation	Verification MUST fail

A tamper-evident seal over the five Core Block fields. Computed as the SHA-256 hash of the canonical JSON serialization of exactly these fields in alphabetical order:

CORE_HASH_FIELDS = [
  "asset_id", "schema_version", "creation_timestamp",
  "hash_original", "creator_id"
]

Bootstrap rule: core_fingerprint MUST NOT be included in its own computation.

Canonicalization (Python reference):

canonical = json.dumps(
    {k: core_block[k] for k in CORE_HASH_FIELDS},
    sort_keys=True, separators=(',', ':')
).encode('utf-8')
core_fingerprint = "sha256-" + hashlib.sha256(canonical).hexdigest()

Example:

"core_fingerprint": "sha256-55e6ccdec47fea01c48da35bc5083025812083cbdbc1706a9be0d6edaf7fa5d3"

`signature`

Property	Value
Type	String or null
Required	SHOULD (null if no signing key available)
Format	`ed25519-<128hex>`
Pattern	`^ed25519-[0-9a-f]{128}$`
Verification level	L2
If null or absent	Verification continues; absence is NOT a failure at L1
If present and non-null	Verifier MUST verify; FAIL if invalid
If present but no public key supplied	Verifier MUST fail with clear error

An Ed25519 signature over the canonical Core Block bytes. Signs only the core fields, not extensions. Use manifest_signature when extensions also need integrity protection.

signature is tied to a specific key, not to creator_id. Key rotation does not change creator_id; it produces a new signature with the new key. The identity persists; the signing tool changes.

Example:

"signature": "ed25519-a1b2c3d4...128hexchars...e5f6"

`manifest_signature`

Property	Value
Type	String or null
Required	SHOULD when sidecar integrity required (null otherwise)
Format	`ed25519-<128hex>`
Pattern	`^ed25519-[0-9a-f]{128}$`
Verification level	L2
If null or absent	Verification continues; absence is NOT a failure at L1
If present and non-null	Verifier MUST verify; FAIL if invalid

A detached Ed25519 signature over the canonical manifest bytes: the entire manifest including extensions, with manifest_signature itself set to null before signing (bootstrap exclusion, prevents circular dependency).

Use manifest_signature when extensions carry material metadata (e.g. soft_binding, ai_model_used, ai_declaration, compliance_eu_art50) that also needs integrity protection. A sidecar with a valid manifest_signature is self-verifying without access to the original asset.

Canonical manifest bytes procedure:

Deep-copy the manifest
Set core.manifest_signature to null
Serialize: sort_keys=True, separators=(',',':'), UTF-8 encoded
Sign the resulting bytes with Ed25519

Example:

"manifest_signature": "ed25519-a1b2c3d4...128hexchars...e5f6"

`anchor_reference`

Property	Value
Type	String or null
Required	SHOULD at L3 (null or absent at L1/L2)
Format	`aios-anchor:<service-id>:<anchor-id>`
Pattern	`^aios-anchor:[a-z0-9_-]+:[a-zA-Z0-9_-]+$`
Verification level	L3
If null or absent	Verification continues without anchor check
If present, verify_anchor=true	Verifier MUST call anchor_resolver; FAIL if mismatch
If present, verify_anchor=false	Emit warning; anchor_verified=false; continue

A URI pointing to an external cryptographic timestamp anchor for this manifest. The anchor independently records that this manifest existed at a specific point in time, without any party being able to retroactively alter the record.

Verifiers MUST treat a null value and an absent field as equivalent: both indicate no anchor is present. Step 13 of the verification process applies only when anchor_reference is a non-null string.

URI structure:

service-id: registered anchor service identifier (e.g. rfc3161, ots-bitcoin)
anchor-id: service-specific record identifier

Example:

"anchor_reference": "aios-anchor:rfc3161:19e83aa5311cfb058c7555fc6b70103c"

`previous_version_anchor`

Property	Value
Type	String or null
Required	MAY (SHOULD for versioned documents)
Format	`aios-anchor:<service-id>:<anchor-id>`
Pattern	`^aios-anchor:[a-z0-9_-]+:[a-zA-Z0-9_-]+$`
Verification level	Informational: verifiers MUST NOT fail if absent or unresolvable
If null or absent	Verification continues normally

Links this manifest to the anchor of its immediately preceding version, creating a cryptographic chain of custody across versions. Used for versioned documents (e.g. the AIOSchema specification itself), asset lineages, and any content that evolves over time while maintaining provenance continuity.

Verifiers MUST NOT fail verification if this field is absent or if the anchor is unresolvable; it is informational provenance, not an integrity check.

Example:

"previous_version_anchor": "aios-anchor:ots-bitcoin:a1b2c3d4e5f6..."

Extension Block Fields

The extensions block is optional: a manifest without it is fully valid. When present, each field within it follows its own requirement level (MAY, SHOULD, or MUST depending on context). Extensions MUST NOT affect the core_fingerprint computation. When manifest_signature is present, all extensions ARE included in the signature scope.

Namespacing Rules

Prefix	Usage
No prefix	Official registered extension fields (see §11 of the spec)
`x-<vendor>-`	Vendor or experimental fields; prefix MUST be registered via the Extension Registry

Custom fields MUST NOT use names that conflict with any Core Block field or any registered extension field name.

Unregistered vendor prefixes MUST NOT be used in conforming manifests. Register vendor prefixes at https://aioschema.org/registry/.

Extension Size Limit

The total serialized size of the extensions object MUST NOT exceed 4KB (4,096 bytes). The Core Block is excluded from this calculation.

Registered Extension Fields

The following fields are defined in §11 of the specification.

Field	Type	Description	Maps to
`camera_model`	String	Device make and model	EXIF Make+Model / `xmp:CreatorTool`
`exposure_time`	String	Shutter speed e.g. `"1/120"`	EXIF ExposureTime
`iso`	Integer	ISO sensitivity value	EXIF ISOSpeedRatings
`software`	String	Software used to create or edit	EXIF Software / `xmp:CreatorTool`
`ai_model_used`	String or null	AI model identifier; null if not AI-generated	`aioschema:aiModelUsed`
`ai_model_version`	String or null	AI model version string	-
`license`	String	SPDX identifier e.g. `"CC-BY-4.0"`	`xmpRights:UsageTerms`
`soft_binding`	Object	pHash soft binding: see below	`aioschema:pHashFingerprint`
`compliance_level`	Integer	Self-declared conformance level (1, 2, or 3). Informational. Not to be confused with `compliance_eu_art50`.	-
`asset_name`	String	Original filename or human-readable asset name	-
`asset_type`	String	Asset type e.g. `"document"`, `"image"`, `"video"`	-
`description`	String (max 256 chars)	Human-readable note about the asset’s provenance context. MUST NOT be used for machine-parseable metadata, rights declarations, or version history.	-
`ai_declaration`	Object	Structured AI disclosure: see §ai_declaration below
`compliance_eu_art50`	Object	EU AI Act Art. 50(4) editorial exemption record: see §compliance_eu_art50 below
`public_key`	String	Base64-encoded Ed25519 public key for self-contained verification: see §public_key below

`soft_binding` Object

Used for perceptual hash soft binding on image and video assets. MUST be present at Level 2 for image and video assets. For other asset types it is optional.

"soft_binding": {
  "algorithm":      "pHash-v1",
  "fingerprint":    "f8e4c2a196b3d750",
  "threshold_info": 5
}

Field	Type	Description
`algorithm`	String	Perceptual hash algorithm. Currently: `pHash-v1`
`fingerprint`	String	16-character hex pHash digest of the asset
`threshold_info`	Integer	Informational only; the threshold used when generating. Verifiers MUST NOT read this value for policy decisions.

Critical: verifiers MUST use their own soft_binding_threshold parameter (default: 5, maximum: 10). The threshold_info in the manifest is documentation only and MUST be ignored for verification policy.

`ai_declaration` Object

Structured boolean fields documenting AI involvement in content creation or modification. When disclosure_required is true, all fields MUST accurately reflect the actual nature of AI involvement.

Field	Type	Requirement	Description
`disclosure_required`	Boolean	MUST	True if AI contributed to this content
`ai_generated`	Boolean	MUST	Content is fully AI-generated
`ai_manipulated`	Boolean	MUST	Existing content was substantially altered by AI
`human_reviewed`	Boolean	MUST	A human reviewed AI-generated content before publication
`standard_editing`	Boolean	OPTIONAL	Only standard editing applied (cropping, colour correction, noise removal). When true, `disclosure_required` MUST be false
`creative_work`	Boolean	OPTIONAL	Artistic, satirical, or fictional work

Constraint: When standard_editing is true, disclosure_required MUST be false.

When human_reviewed is true, compliance_eu_art50 SHOULD be present.

Example:

"ai_declaration": {
  "disclosure_required": true,
  "ai_generated": true,
  "ai_manipulated": false,
  "human_reviewed": true,
  "standard_editing": false,
  "creative_work": false
}

`compliance_eu_art50`

Property	Value
Type	Object
Required	MAY (MUST when claiming EU AI Act Art. 50(4) editorial exemption)
Verification level	Warning on incomplete exemption fields

Records that a qualifying editorial review occurred and its nature.

All fields are OPTIONAL in the JSON Schema. The fields marked MUST below MUST be present when the publisher claims the editorial exemption. A manifest that includes compliance_eu_art50 without the required fields remains a fully valid AIOSchema manifest; it does not assert the editorial exemption.

Field	Type	Required for exemption	Description
`editorial_responsibility`	String	MUST	Organisation name or role title of the person holding editorial responsibility under EU AI Act Art. 50(4). Not a personal name.
`review_type`	String (enum)	MUST	Nature of review performed.
`reviewer_id`	String (`ed25519-fp-<32hex>`)	OPTIONAL	Cryptographic non-identifying anchor (Ed25519 public key fingerprint). Does not expose personal identity.

review_type MUST be one of:

substantive: deliberate examination of content substance by a person with relevant competence and professional judgement.
editorial-control: editorial control exercised by a responsible person.

Both values satisfy the EU AI Act Art. 50(4) editorial exemption.

Verifier behaviour: Verifiers SHOULD emit a warning (not a failure) when compliance_eu_art50 is present but review_type is absent:

"compliance_eu_art50.review_type absent: set to \"substantive\" or \"editorial-control\""

Example:

"compliance_eu_art50": {
  "editorial_responsibility": "Editorial Team, Example Media Ltd",
  "review_type": "substantive"
}

`public_key`

Property	Value
Type	String
Required	MAY (enables self-contained verification)
Format	Base64-encoded raw 32-byte Ed25519 public key
Verification level	L2 (when `signature` or `manifest_signature` present)

Embeds the Ed25519 public key directly in the manifest, enabling offline verification without network access or an external key registry.

Fingerprint cross-check (Normative):

A verifier MUST validate the embedded key against creator_id before using it:

Decode the Base64 value to raw bytes.
Compute SHA-256(raw_bytes) and take the first 16 bytes (32 hex characters).
Construct the expected creator_id: ed25519-fp-<32hex>.
Compare against the manifest creator_id using timing-safe equality.
If they do not match: FAIL with public_key_fingerprint_match=false.
If they match: proceed with signature verification.

When both extensions.public_key and a key from Creator Key Discovery are available, the verifier SHOULD prefer the discovered key and MUST verify both keys are identical. A mismatch MUST produce a warning and SHOULD cause verification to fail.

Example:

"public_key": "MCowBQYDK2VwAyEAj4VZRK5VJThKGx8LYXeF8YvjNWKpWnLqM3rXeV4Q9sM="

Verification Result Fields

A conforming verifier returns a result object with the following fields:

Field	Type	Description
`success`	Boolean	True if verification passed at the requested level
`message`	String	Human-readable result summary
`match_type`	`"hard"` \| `"soft"` \| null	How the asset hash was matched
`signature_verified`	Boolean	True if `signature` was present and verified
`manifest_signature_verified`	Boolean	True if `manifest_signature` was present and verified
`anchor_checked`	Boolean	True if anchor verification was attempted
`anchor_verified`	Boolean	True if anchor verification succeeded
`public_key_fingerprint_match`	Boolean or null	`true` if `extensions.public_key` fingerprint matched `creator_id`; `false` if mismatch; `null` if `extensions.public_key` absent
`warnings`	Array<String>	Non-fatal issues encountered during verification

Sidecar Naming Convention

<original-filename><original-extension>.aios.json

Asset filename	Sidecar filename
`photo.jpg`	`photo.jpg.aios.json`
`video.mp4`	`video.mp4.aios.json`
`document.pdf`	`document.pdf.aios.json`
`report.md`	`report.md.aios.json`

Field Quick Reference

Field	Block	Required	Level	In FP
`asset_id`	core	MUST	L1	✓
`schema_version`	core	MUST	L1	✓
`creation_timestamp`	core	MUST	L1	✓
`hash_original`	core	MUST	L1	✓
`creator_id`	core	MUST	L1	✓
`core_fingerprint`	core	MUST	L1	-
`signature`	core	SHOULD	L2	-
`manifest_signature`	core	SHOULD	L2	-
`anchor_reference`	core	SHOULD	L3	-
`previous_version_anchor`	core	MAY	info	-
`soft_binding`	extensions	MUST (image/video at L2)	L2	-
`ai_model_used`	extensions	MAY	-	-
`license`	extensions	MAY	-	-
`compliance_level`	extensions	MAY	info	-
`asset_name`	extensions	MAY	-	-
`asset_type`	extensions	MAY	-	-
`description`	extensions	MAY	-	-
`ai_declaration`	extensions	MAY	-	-
`compliance_eu_art50`	extensions	MAY	-	-
`public_key`	extensions	MAY	L2	-

FP = included in core_fingerprint computation

signature and manifest_signature are SHOULD at Level 2: they MUST be present when a signing key is available. A manifest without them is still valid at Level 1.

soft_binding MUST be present at Level 2 for image and video assets. For other asset types it is optional.

ai_declaration is MAY for general use. When a publisher asserts EU AI Act Art. 50 compliance, it MUST be present and MUST accurately reflect AI involvement.

compliance_eu_art50 is MAY for general use. When a publisher claims the EU AI Act Art. 50(4) editorial exemption, it MUST be present with editorial_responsibility and review_type populated.

public_key is MAY. When present, the verifier MUST perform the fingerprint cross-check against creator_id before using it for signature verification.

Deprecated Fields

Field	Deprecated in	Removed in	Notes
`hash_schema_block`	v0.5.5	v0.6	Accepted as alias for `core_fingerprint`. Use `core_fingerprint`.

Deferred Fields (Informational)

The following fields are planned for future versions. Implementations MUST NOT use these names for custom fields; they are reserved.

Field	Target version	Description
`creator_keyref`	v0.6	Reference to the specific key used for `signature`; enables key rotation tracking without changing `creator_id`
`extensions_version`	v0.6	Version string for the extensions block schema
`rights`	v0.6	Structured rights and permissions field: AI usage declarations, licensing signals

Extension Registry

Official extension fields are registered in the AIOSchema Extension Registry at https://aioschema.org/registries/extensions/. Vendor prefix registration is available at https://aioschema.org/registry/.

No custom field MAY use a name that conflicts with any Core Block field or any registered extension field name, with or without a prefix.

Changelog

All versions of this document are backward compatible with v0.5.5 manifests. A v0.5.5 verifier will correctly process any v0.5.5 manifest. A v0.5.6 verifier MUST accept all schema_version values from "0.1" through "0.5.6".

Version	Date	Changes
v0.5.6	2026-06-05	Added `ai_declaration` extension field (structured AI involvement disclosure). Added `compliance_eu_art50` extension field (EU AI Act Art. 50(4) editorial exemption record): two fields required when claiming exemption: `editorial_responsibility` and `review_type`; `reviewer_id` OPTIONAL. Added `public_key` extension field (self-contained verification via embedded Ed25519 public key) with normative fingerprint cross-check. Added `public_key_fingerprint_match` to VerificationResult. Added extension size limit: 4KB maximum on serialized `extensions` object. Added Extension Registry and vendor prefix registration requirement. Updated `description` field: 256-char maximum, provenance context only. `schema_version` accepted values extended to include `"0.5.6"`.
v0.5.5	2026-03-17	Initial release of this document. `hash_schema_block` deprecated as alias for `core_fingerprint`; accepted by v0.5.5 and later verifiers; scheduled for removal in v0.6.

AIOSchema Field Reference Guide

Version 0.5.6

Manifest Structure

Core Block Fields

asset_id [FP]

schema_version [FP]

creation_timestamp [FP]

hash_original [FP]

creator_id [FP]

core_fingerprint

signature

manifest_signature

anchor_reference

previous_version_anchor

Extension Block Fields

Namespacing Rules

Extension Size Limit

Registered Extension Fields

soft_binding Object

ai_declaration Object

compliance_eu_art50

public_key

Verification Result Fields

Sidecar Naming Convention

Field Quick Reference

Deprecated Fields

Deferred Fields (Informational)

Extension Registry

Changelog

`asset_id` [FP]

`schema_version` [FP]

`creation_timestamp` [FP]

`hash_original` [FP]

`creator_id` [FP]

`core_fingerprint`

`signature`

`manifest_signature`

`anchor_reference`

`previous_version_anchor`

`soft_binding` Object

`ai_declaration` Object

`compliance_eu_art50`

`public_key`