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ISCC Metadata#

IEP: 0012
Title: ISCC Metadata
Author: Titusz Pan tp@iscc.foundation
Comments: https://github.com/iscc/iscc-ieps/issues/17
Status: DRAFT
Type: Core
License: CC-BY-4.0
Created: 2022-09-28
Updated: 2024-01-08

Note

This document is a DRAFT contributed as input to ISO TC 46/SC 9/WG 18. The final version is developed at the International Organization for Standardization as ISO/DIS 24138

1. General#

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

  1. use the JSON-LD syntax;
  2. be described by a versioned and machine-readable JSON Schema 1;

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:

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

2. Seed metadata#

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

3. Technical metadata#

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

4. Other metadata#

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

5. Bibliography#

  1. 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 ↩