Multipart MIME #5

AdamSobieski · 2026-08-01T21:02:56Z

AdamSobieski
Aug 1, 2026
Maintainer

Introduction

Multipart MIME messages could be used for representing knowledge, argumentation, and other kinds of data intended for interchange between software applications and systems.

Towards these objectives, two new header fields are considered: Content-Context and Content-Relation. The first, Content-Context, is for referencing resources with which to describe and validate multipart MIME messages. The second, Content-Relation, is for labeling and distinguishing parts of messages.

A new multipart-MIME-based resource type is also indicated for describing and validating multipart MIME messages and their parts' contents.

Use Cases

Some use cases for multipart MIME messages and (compressed) archive resources are listed below.

A first use case involves using multipart MIME messages with metadata parts for clipboarding, dragging-and-dropping, and other interprocess communication scenarios.

A second use case involves data provenance. One could provide bibliographic references (e.g., text/x-bibtex) alongside data, e.g., content, selections, excerpts, or quotations.

A third use case involves bundling data-table schemas with one or more more data tables (e.g., text/csv, text/tab-separated-values). As envisioned, metadata schema resources, e.g., CSVW metadata (application/csvm+json), describing the tables' schemas could accompany one or more data tables. See also: SQLite3 database files (application/x-sqlite3).

A fourth use case involves including rules, grammars, schemas, or ontologies with which to validate one or more resources. For XML-based resources, there is an xsi:schemaLocation attribute for referring to XML schema resources which could be stored elsewhere in a multipart MIME message or archive file. For RDF-based resources, there are dct:conformsTo and dash:shape properties for referring to other resources, i.e., SHACL resources.

A fifth use case involves 3D models (e.g., model/gltf+json, model/xsd+xml, model/vnd.usda) which could be accompanied by additional graphics, audio, animation, metadata, semantics, and/or accessibility-related resources. See also: Universal Scene Description packages (model/vnd.usdz+zip).

A sixth use case involves enabling resources, e.g., source-code resources (e.g., text/x-python) or software projects, to be accompanied by discussion transcripts (e.g., application/vnd.vcon+json) about them.

A seventh use case involves artificial-intelligence systems, e.g., agentic systems, which could produce, store, load, transmit, and consume multiple resources bundled together as multipart MIME messages or (compressed) archive files.

Examples

The following examples showcase Content-Context and Content-Relation header fields for multipart MIME messages.

Example 1

The following example shows a multipart MIME message with metadata indicating that its main part references a bibliographic resource.

Mime-Version: 1.0
Message-ID: <12345678>
Content-Context: <https://www.example.org/structure.mimeld>
Content-Type: multipart/related; boundary="boundary-example"

--boundary-example

Content-ID: <part1>
Content-Relation: metadata
Content-Type: text/turtle

@prefix dc: <http://purl.org/dc/terms/> .
@prefix example: <http://example.org/> .

<mid:12345678> dc:hasPart <cid:part1>, <cid:part2>, <cid:part3> ;
    example:hasMainPart <cid:part2> .

<cid:part1> dc:format "text/turtle" .

<cid:part2> dc:format "text/plain" ;
    dc:language "en" ;
    dc:references <cid:part3#archer2010climate> .

<cid:part3> dc:format "text/x-bibtex" .

--boundary-example

Content-ID: <part2>
Content-Relation: main
Content-Type: text/plain
Content-Language: en

Climate change is caused by human activities. Therefore, we should reduce carbon emissions.

--boundary-example

Content-ID: <part3>
Content-Relation: supplemental
Content-Type: text/x-bibtex

@book{archer2010climate,
    title={The climate crisis: An introductory guide to climate change},
    author={Archer, David and Rahmstorf, Stefan},
    year={2010},
    publisher={Cambridge University Press}
}

--boundary-example--

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Example 2

The following example, drawing inspiration from the Web Annotation Data Model, shows a multipart MIME message with metadata expressing that its main part is a selection of another of its parts referenced by URL.

Mime-Version: 1.0
Message-ID: <12345678>
Content-Context: <https://www.example.org/structure.mimeld>
Content-Type: multipart/related; boundary="boundary-example"

--boundary-example

Content-ID: <part1>
Content-Relation: metadata
Content-Type: text/turtle

@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix dc: <http://purl.org/dc/terms/> .
@prefix oa: <http://www.w3.org/ns/oa#> .
@prefix example: <http://example.org/> .

<mid:12345678> dc:hasPart <cid:part1>, <cid:part2>, <cid:part3> ;
    example:hasMainPart <cid:part2> .

<cid:part1> dc:format "text/turtle" .

<cid:part2> dc:format "text/plain" ;
    dc:language "en" ;
    dc:references <cid:part3> .

<cid:part3> dc:format "text/html" ;
    dc:language "en" .

[ a oa:Annotation ;
    oa:hasTarget [ oa:hasSource <cid:part3> ;
                   oa:hasSelector [ a oa:FragmentSelector ;
                                    rdf:value "para5" ;
                                    oa:refinedBy [ oa:TextQuoteSelector ;
                                                   oa:exact <cid:part2> ] ] ] ] .

--boundary-example

Content-ID: <part2>
Content-Relation: main
Content-Type: text/plain
Content-Language: en

Climate change is caused by human activities. Therefore, we should reduce carbon emissions.

--boundary-example

Content-ID: <part3>
Content-Relation: supplemental
Content-Type: text/plain
Content-Language: en
Content-Location: https://www.example.org/resource.html
Date: Mon, 10 Aug 2026 14:25:00 GMT

--boundary-example--

Example 3

The following example shows a multipart MIME message with metadata indicating that its main part offers alternative formats for an argument claim while referencing an attached spreadsheet as evidence.

Mime-Version: 1.0
Message-ID: <12345678>
Content-Context: <https://www.example.org/structure.mimeld>
Content-Type: multipart/related; boundary="boundary-example"

--boundary-example

Content-ID: <part1>
Content-Relation: metadata
Content-Type: text/turtle

@prefix dc: <http://purl.org/dc/terms/> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
@prefix example: <http://example.org/>.

<mid:12345678> dc:created "2025-06-29 20:00:00.000" ;
    dc:creator [ a foaf:Person ; foaf:name "Bob Smith" ] ;
    dc:hasPart <cid:part1>, <cid:part2>, <cid:part3> ;
    example:hasMainPart <cid:part2> .

<cid:part1> dc:format "text/turtle" .

<cid:part2> dc:hasPart <cid:part2_1>, <cid:part2_2>, <cid:part2_3> ;
    dc:format "multipart/alternative" .

<cid:part2_1> dc:isFormatOf <cid:part2_2>, <cid:part2_3> ;
    dc:format "text/plain" ;
    dc:language "en" ;
    dc:references <cid:part3> .

<cid:part2_2> dc:isFormatOf <cid:part2_1>, <cid:part2_3> ;
    dc:format "application/xhtml+xml" ;
    dc:language "en" ;
    dc:references <cid:part3> .

<cid:part2_3> dc:isFormatOf <cid:part2_1>, <cid:part2_2> ;
    dc:format "text/turtle" ;
    dc:references <cid:part3> .

<cid:part3> dc:format "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" ;
    dc:language "en" .

--boundary-example

Content-ID: <part2>
Content-Relation: main
Content-Type: multipart/alternative; boundary="nested-boundary"

--nested-boundary

Content-ID: <part2_1>
Content-Type: text/plain
Content-Language: en

Climate change is caused by human activities. Therefore, we should reduce carbon emissions.

--nested-boundary

Content-ID: <part2_2>
Content-Type: application/xhtml+xml
Content-Language: en

<html xmlns="http://www.w3.org/1999/xhtml"><body>
<span><a rel="evidence" href="cid:part3">Climate change is caused by human activities.</a>
Therefore, we should reduce carbon emissions.</span>
</body></html>

--nested-boundary

Content-ID: <part2_3>
Content-Type: text/turtle
Content-Language: en

@prefix aif: <http://www.arg.dundee.ac.uk/aif#> .
@prefix example: <http://example.org/> .
@prefix extension: <http://extension.org/> .

example:Node1 a aif:I-node ;
    aif:claimText "Climate change is caused by human activities." .

example:Node2 a aif:RA-node ;
    aif:hasPremise example:Node1 ;
    aif:hasConclusion example:Node3 .

example:Node3 a aif:I-node ;
    aif:claimText "We should reduce carbon emissions." .

example:Node4 a extension:E-node ;
    extension:hasEvidence <cid:part3> .

example:Node5 a extension:ES-node ;
    extension:supported example:Node1 ;
    extension:supportedBy example:Node4 .

--nested-boundary--

--boundary-example

Content-ID: <part3>
Content-Relation: supplemental
Content-Disposition: attachment; filename="evidence.xslx"
Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
Content-Language: en
Content-Transfer-Encoding: base64

TG9yZW0gaXBzdW0gZG9sb3Igc2l0IGFtZXQsIGNvbnNlY3RldHVyIGFkaXBpc2NpbmcgZWxpdC4g
U2VkIGRvIGVpdXNtb2QgdGVtcG9yIGluY2lkaWR1bnQgdXQgbGFib3JlIGV0IGRvbG9yZSBtYWdu
YSBhbGlxdWEuIFV0IGVuaW0gYWQgbWluaW0gdmVuaWFtLCBxdWlzIG5vc3RydWQgZXhlcmNpdGF0
aW9uIHVsbGFtY28gbGFib3JpcyBuaXNpIHV0IGFsaXF1aXAgZXggZWEgY29tbW9kbyBjb25zZXF1
YXQuCg==

--boundary-example--

Example 4

How might multipart MIME messages be of use for storing and transmitting knowledge graphs with accompanying embedding vectors? Some possibilities are presented below.

Firstly, embedding vectors can be represented as RDF literals per the RDF Tensor project.

Mime-Version: 1.0
Message-ID: <12345678>
Content-Context: <https://www.example.org/structure.mimeld>
Content-Type: multipart/related; boundary="boundary-example"

--boundary-example

Content-ID: <part1>
Content-Relation: metadata
Content-Type: text/turtle

@prefix dc: <http://purl.org/dc/terms/> .
@prefix example: <http://example.org/>.

<mid:12345678> dc:hasPart <cid:part1>, <cid:part2> ;
    example:hasMainPart <cid:part2> .

--boundary-example

Content-ID: <part2>
Content-Relation: main
Content-Type: text/turtle

@prefix example: <http://example.org/> .
@prefix emb: <http://embeddings.org/> .
@prefix tensor: <https://w3id.org/rdf-tensor/vocab#> .

example:Node1 emb:hasEmbedding "{\"type\": \"float32\", \"shape\": [3], \"data\": [1.0, 2.0, 3.0]}"^^tensor:DataTensor .
example:Node2 emb:hasEmbedding "{\"type\": \"float32\", \"shape\": [3], \"data\": [4.0, 5.0, 6.0]}"^^tensor:DataTensor .

--boundary-example--

Secondly, noticing that JSON content is in the literals, above, one could extract those parts into resources which could then be referenced by URLs. In this case, cid: URLs.

Mime-Version: 1.0
Message-ID: <12345678>
Content-Context: <https://www.example.org/structure.mimeld>
Content-Type: multipart/related; boundary="boundary-example"

--boundary-example

Content-ID: <part1>
Content-Relation: metadata
Content-Type: text/turtle

@prefix dc: <http://purl.org/dc/terms/> .
@prefix example: <http://example.org/>.

<mid:12345678> dc:hasPart <cid:part1>, <cid:part2>, <cid:part3>, <cid:part4> ;
    example:hasMainPart <cid:part2> .

--boundary-example

Content-ID: <part2>
Content-Relation: main
Content-Type: text/turtle

@prefix example: <http://example.org/> .
@prefix emb: <http://embeddings.org/> .

example:Node1 emb:hasEmbedding <cid:part3> .
example:Node2 emb:hasEmbedding <cid:part4> .

--boundary-example

Content-ID: <part3>
Content-Relation: supplemental
Content-Type: application/tensor+json

{ "type": "float32", "shape": [3], "data": [1.0, 2.0, 3.0] }

--boundary-example

Content-ID: <part4>
Content-Relation: supplemental
Content-Type: application/tensor+json

{ "type": "float32", "shape": [3], "data": [4.0, 5.0, 6.0] }

--boundary-example--

Thirdly, one could use CBOR instead of JSON to represent tensors.

Mime-Version: 1.0
Message-ID: <12345678>
Content-Context: <https://www.example.org/structure.mimeld>
Content-Type: multipart/related; boundary="boundary-example"

--boundary-example

Content-ID: <part1>
Content-Relation: metadata
Content-Type: text/turtle

@prefix dc: <http://purl.org/dc/terms/> .
@prefix example: <http://example.org/>.

<mid:12345678> dc:hasPart <cid:part1>, <cid:part2>, <cid:part3>, <cid:part4> ;
    example:hasMainPart <cid:part2> .

--boundary-example

Content-ID: <part2>
Content-Relation: main
Content-Type: text/turtle

@prefix example: <http://example.org/> .
@prefix emb: <http://embeddings.org/> .

example:Node1 emb:hasEmbedding <cid:part3> .
example:Node2 emb:hasEmbedding <cid:part4> .

--boundary-example

Content-ID: <part3>
Content-Relation: supplemental
Content-Type: application/tensor+cbor
Content-Transfer-Encoding: base64

uQADZHR5cGVnZmxvYXQzMmVzaGFwZYEDZGRhdGGDAQID

--boundary-example

Content-ID: <part4>
Content-Relation: supplemental
Content-Type: application/tensor+cbor
Content-Transfer-Encoding: base64

uQADZHR5cGVnZmxvYXQzMmVzaGFwZYEDZGRhdGGDBAUG

--boundary-example--

Fourthly, one could use the Safetensors format. Note that cid: URLs can make use of fragment identifiers to refer to parts of resources.

Mime-Version: 1.0
Message-ID: <12345678>
Content-Context: <https://www.example.org/structure.mimeld>
Content-Type: multipart/related; boundary="boundary-example"

--boundary-example

Content-ID: <part1>
Content-Relation: metadata
Content-Type: text/turtle

@prefix dc: <http://purl.org/dc/terms/> .
@prefix example: <http://example.org/>.

<mid:12345678> dc:hasPart <cid:part1>, <cid:part2>, <cid:part3> ;
    example:hasMainPart <cid:part2> .

--boundary-example

Content-ID: <part2>
Content-Relation: main
Content-Type: text/turtle

@prefix example: <http://example.org/> .
@prefix emb: <http://embeddings.org/> .

example:Node1 emb:hasEmbedding <cid:part3#key1> .
example:Node2 emb:hasEmbedding <cid:part3#key2> .

--boundary-example

Content-ID: <part3>
Content-Relation: supplemental
Content-Type: application/vnd.huggingface.safetensors
Content-Transfer-Encoding: base64

eAAAAAAAAAB7ImtleTEiOnsiZHR5cGUiOiJGMzIiLCJzaGFwZSI6WzNdLCJkYXRhX29mZnNldHMi
OlswLDEyXX0sImtleTIiOnsiZHR5cGUiOiJGMzIiLCJzaGFwZSI6WzNdLCJkYXRhX29mZnNldHMi
OlsxMiwyNF19fSAgICAAAIA/AAAAQAAAQEAAAIBAAACgQAAAwEA=

--boundary-example--

Fifthly, one could use the HDF5 format.

Mime-Version: 1.0
Message-ID: <12345678>
Content-Context: <https://www.example.org/structure.mimeld>
Content-Type: multipart/related; boundary="boundary-example"

--boundary-example

Content-ID: <part1>
Content-Relation: metadata
Content-Type: text/turtle

@prefix dc: <http://purl.org/dc/terms/> .
@prefix example: <http://example.org/>.

<mid:12345678> dc:hasPart <cid:part1>, <cid:part2>, <cid:part3> ;
    example:hasMainPart <cid:part2> .

--boundary-example

Content-ID: <part2>
Content-Relation: main
Content-Type: text/turtle

@prefix example: <http://example.org/> .
@prefix emb: <http://embeddings.org/> .

example:Node1 emb:hasEmbedding <cid:part3#h5(/key1)> .
example:Node2 emb:hasEmbedding <cid:part3#h5(/key2)> .

--boundary-example

Content-ID: <part3>
Content-Relation: supplemental
Content-Type: application/x-hdf5
Content-Transfer-Encoding: base64
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--boundary-example--

Towards a Format for the Description and Validation of Multipart MIME Messages

In the above examples, a .mimeld resource is referenced via Content-Context header fields. What might such resources resemble? Such resources could be multipart MIME messages utilizing JSON-LD, in a message part, to describe valid multipart MIME messages and their parts. Using JSON-LD, one could describe messages' parts' text labels, semantic IRIs, cardinalities, MIME types, and means of content validation.

At the URL: https://www.example.org/structure.mimeld, a .mimeld resource might resemble something along the lines of:

Mime-Version: 1.0
Content-Context: <https://www.example.org/context.mimeld>
Content-Type: multipart/related; boundary="boundary-example"

--boundary-example

Content-Relation: context
Content-Type: application/ld+json

{
  "@context": "...",
  "content": [
    {
      "type": "multipart/related",
      "parts": {
        "metadata": {
          "cardinality": { "min": 0, "max": 1 },
          "content": [
            {
              "type": "application/ld+json",
              "validation": { "location": "https://www.example.org/resource.schema.json", "type": "application/schema+json" }
            },
            {
              "type": "text/turtle",
              "validation": { "location": "https://www.example.org/resource.shacl", "type": "text/turtle" }
            }
          ]
        },
        "main": {
          "cardinality": { "min": 1, "max": 1 }
        },
        "supplemental": {
          "cardinality": { "min": 0 }
        }
      }
    }
  ]
}

--boundary-example--

Note that the content arrays are disjunctive collections.

At the URL: https://www.example.org/context.mimeld, envisioned as being self-referential and self-describing, a .mimeld resource might resemble something along the lines of:

Mime-Version: 1.0
Message-ID: <0>
Content-Context: <mid:0>
Content-Type: multipart/related; boundary="boundary-example"

--boundary-example

Content-Relation: context
Content-Type: application/ld+json

{
  "@context": "...",
  "content": [
    {
      "type": "multipart/related",
      "parts": {
        "context": {
          "cardinality": { "min": 1, "max": 1 },
          "content": [ { "type": "application/ld+json" } ]
        }
      }
    }
  ]
}

--boundary-example--

As the resources under discussion are multipart MIME messages, instead of having to use external URLs to reference any .mimeld resources, the .mimeld resources could be placed inline in messages' parts and referenced using the cid: URL scheme in the Content-Context header field. Similarly, any referenced resources for validating messages' parts (e.g., grammars, schemas, ontologies, and shapes) could be, instead, inline in messages' parts.

Conclusion

What do you think about these ideas? Thank you.

BigBlueHat · 2026-08-11T23:11:57Z

BigBlueHat
Aug 11, 2026

This bit of history is worth a look: https://www.w3.org/TR/2015/WD-web-packaging-20150115/

It's very similar to what you describe here with clearly similar use cases in mind.

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Multipart MIME #5

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AdamSobieski Aug 1, 2026 Maintainer

Introduction

Use Cases

Examples

Example 1

Example 2

Example 3

Example 4

Towards a Format for the Description and Validation of Multipart MIME Messages

Conclusion

Replies: 1 comment

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BigBlueHat Aug 11, 2026

AdamSobieski
Aug 1, 2026
Maintainer

BigBlueHat
Aug 11, 2026