ISCC Metadata#

IEP:	0012
Title:	ISCC Metadata
Author:	Titusz Pan tp@iscc.io
Comments:	https://github.com/iscc/iscc-ieps/issues/17
Status:	DRAFT
Type:	Core
License:	CC-BY-4.0
Created:	2022-09-28
Updated:	2024-11-30

Note

This document is a DRAFT contributed as input to ISO TC 46/SC 9/WG 18. The final version is published under ISO 24138:2024.

1. General#

In the process of creating an ISCC, additional metadata can be generated or added. Such ISCC metadata shall:

If ISCC metadata is generated or added, it shall include at least the elements defined in Table 1:

Element	Description
`@context`	The JSON-LD context URI for ISCC metadata. Example: https://purl.org/iscc/context/iscc.jsonld
`@type`	The type of digital content identified by the ISCC as specified by the JSON-LD context. Example classes: `CreativeWork`, `TextDigitalDocument`, `ImageObject`, `AudioObject`, `VideoObject`
`$shema`	The JSON schema URI for ISCC metadata. Example: http://purl.org/iscc/schema/iscc.json
`iscc`	ISCC of the identified digital asset in canonical form.

Table 1 – Minimal set of elements for ISCC metadata

Metadata as outlined in Table 2, 3, and 4 should:

support automated technical identification, integrity verification and general digital asset and metadata management use-cases;
prioritize technical information which can be measured, extracted, and verified automatically and reliably based on the identified digital asset itself;
be regarded as neither authoritative nor canonical, in the absence of other verifying information;
be extensible to accommodate different use cases.

Seed metadata is used as input for generating the Meta-Code and repeated as output after ISCC processing (see Table 2).

Element	Description
`name`	The title or name of the intangible creation manifested by the identified digital asset.
`description`	Description of the digital content identified by the ISCC. Any user presentable text string indicative of the identity of the referent may be used.
`meta`	Subject, industry, or use-case specific metadata, encoded as Data-URL.

Table 2 – Seed metadata elements

Technical metadata that can be generated during ISCC processing of the various ISCC-UNITs is shown in Table 3.

Element	Description
`filename`	Filename of the digital asset (without directory path).
`keywords`	Keywords or tags automatically extracted from the content.
`langauge`	Language(s) used in the content (BCP-47) in weighted order.
`characters`	Number of text characters (code points after Unicode normalization).
`filesize`	Length of data in bytes.
`mediatype`	Media type of the digital asset.
`thumbnail`	URI of an autogenerated user-presentable thumbnail-image that serves as a preview of the digital content. The URI may be a Data-URL.
`duration`	Duration of audio or video content in seconds.
`width`	Width of visual media in number of pixels.
`height`	Height of visual media in number of pixels.
`fps`	Frames per second for video assets.
`datahash`	Cryptographic multihash of the digital asset.
`metahash`	Cryptographic multihash of the seed metadata. (The hash is created from `name` and `description` elements or the `meta` element if supplied. (See IEP-0002 - Meta-Hash processing)
`tophash`	Cryptographic multihash of the concatenation of metahash and datahash. Used as a binding identifier of asset data and seed metadata.

Table 3 – Technical metadata elements

Other metadata that may be extracted from the asset or separately added to the output of ISCC processing is shown in Table 4.

Element	Description
`identifier`	Other identifier(s) such as those defined by ISO/TC 46/SC 9, identifying the entity of which the digital asset is a full or partial manifestation, expressed using the URI syntax defined in RFC 3986.

Table 4 – Other metadata elements

IETF, draft-bhutton-json-schema-01 — JSON Schema: A Media Type for Describing JSON Documents
Available at https://datatracker.ietf.org/doc/html/draft-bhutton-json-schema-01 ↩