Internet Engineering Task Force L.R. van Kammen Internet-Draft 4 September 2023 Intended status: Informational XR Fragments draft-XRFRAGMENTS-leonvankammen-00 Abstract This draft offers a specification for 4D URLs & navigation, to link 3D scenes and text together with- or without a network-connection. The specification promotes spatial addressibility, sharing, navigation, query-ing and tagging interactive (text)objects across for (XR) Browsers. XR Fragments allows us to enrich existing dataformats, by recursive use of existing proven technologies like URI Fragments (https://en.wikipedia.org/wiki/URI_fragment) and visual-meta (https://visual-meta.info). Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 7 March 2024. Copyright Notice Copyright (c) 2023 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components van Kammen Expires 7 March 2024 [Page 1] Internet-Draft XR Fragments September 2023 extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3 3. Core principle . . . . . . . . . . . . . . . . . . . . . . . 4 4. List of URI Fragments . . . . . . . . . . . . . . . . . . . . 4 5. List of metadata for 3D nodes . . . . . . . . . . . . . . . . 4 6. Navigating 3D . . . . . . . . . . . . . . . . . . . . . . . . 5 7. Embedding 3D content . . . . . . . . . . . . . . . . . . . . 5 8. Text in XR (tagging,linking to spatial objects) . . . . . . . 6 8.1. Default Data URI mimetype . . . . . . . . . . . . . . . . 8 8.2. URL and Data URI . . . . . . . . . . . . . . . . . . . . 9 8.3. BibTeX as lowest common denominator for tagging/triple . 10 8.4. XR text (BibTeX) example parser . . . . . . . . . . . . . 11 9. HYPER copy/paste . . . . . . . . . . . . . . . . . . . . . . 13 10. XR Fragment queries . . . . . . . . . . . . . . . . . . . . . 13 10.1. including/excluding . . . . . . . . . . . . . . . . . . 14 10.2. Query Parser . . . . . . . . . . . . . . . . . . . . . . 14 10.3. XR Fragment URI Grammar . . . . . . . . . . . . . . . . 15 11. Security Considerations . . . . . . . . . . . . . . . . . . . 15 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 15 1. Introduction How can we add more features to existing text & 3D scenes, without introducing new dataformats? Historically, there's many attempts to create the ultimate markuplanguage or 3D fileformat. However, thru the lens of authoring their lowest common denominator is still: plain text. XR Fragments allows us to enrich existing dataformats, by recursive use of existing technologies: 1. addressibility and navigation of 3D scenes/objects: URI Fragments (https://en.wikipedia.org/wiki/URI_fragment) + src/href spatial metadata 2. hasslefree tagging across text and spatial objects using BiBTeX (visual-meta (https://visual-meta.info) e.g.) | NOTE: The chapters in this document are ordered from highlevel to | lowlevel (technical) as much as possible van Kammen Expires 7 March 2024 [Page 2] Internet-Draft XR Fragments September 2023 2. Conventions and Definitions +===============+===========================================+ | definition | explanation | +===============+===========================================+ | human | a sentient being who thinks fuzzy, | | | absorbs, and shares thought (by plain | | | text, not markuplanguage) | +---------------+-------------------------------------------+ | scene | a (local/remote) 3D scene or 3D file | | | (index.gltf e.g.) | +---------------+-------------------------------------------+ | 3D object | an object inside a scene characterized by | | | vertex-, face- and customproperty data. | +---------------+-------------------------------------------+ | metadata | custom properties of text, 3D Scene or | | | Object(nodes), relevant to machines and a | | | human minority (academics/developers) | +---------------+-------------------------------------------+ | XR fragment | URI Fragment with spatial hints | | | (#pos=0,0,0&t=1,100 e.g.) | +---------------+-------------------------------------------+ | src | (HTML-piggybacked) metadata of a 3D | | | object which instances content | +---------------+-------------------------------------------+ | href | (HTML-piggybacked) metadata of a 3D | | | object which links to content | +---------------+-------------------------------------------+ | query | an URI Fragment-operator which queries | | | object(s) from a scene (#q=cube) | +---------------+-------------------------------------------+ | visual-meta | visual-meta (https://visual.meta.info) | | | data appended to text which is indirectly | | | visible/editable in XR. | +---------------+-------------------------------------------+ | requestless | opposite of networked metadata (RDF/HTML | | metadata | request-fanouts easily cause framerate- | | | dropping, hence not used a lot in games). | +---------------+-------------------------------------------+ | FPS | frames per second in spatial experiences | | | (games,VR,AR e.g.), should be as high as | | | possible | +---------------+-------------------------------------------+ | introspective | inward sensemaking ("I feel this belongs | | | to that") | +---------------+-------------------------------------------+ | extrospective | outward sensemaking ("I'm fairly sure | | | John is a person who lives in oklahoma") | van Kammen Expires 7 March 2024 [Page 3] Internet-Draft XR Fragments September 2023 +---------------+-------------------------------------------+ | ◻ | ascii representation of an 3D object/mesh | +---------------+-------------------------------------------+ Table 1 3. Core principle XR Fragments strives to serve humans first, machine(implementations) later, by ensuring hasslefree text-to-thought feedback loops. This also means that the repair-ability of machine-matters should be human friendly too (not too complex). | "When a car breaks down, the ones without turbosupercharger are | easier to fix" 4. List of URI Fragments +==========+=========+==============+============================+ | fragment | type | example | info | +==========+=========+==============+============================+ | #pos | vector3 | #pos=0.5,0,0 | positions camera to xyz- | | | | | coord 0.5,0,0 | +----------+---------+--------------+----------------------------+ | #rot | vector3 | #rot=0,90,0 | rotates camera to xyz- | | | | | coord 0.5,0,0 | +----------+---------+--------------+----------------------------+ | #t | vector2 | #t=500,1000 | sets animation-loop range | | | | | between frame 500 and 1000 | +----------+---------+--------------+----------------------------+ | #...... | string | #.cubes | object(s) of interest | | | | #cube | (fragment to object name | | | | | or class mapping) | +----------+---------+--------------+----------------------------+ Table 2 | xyz coordinates are similar to ones found in SVG Media Fragments 5. List of metadata for 3D nodes +=======+========+================+============================+ | key | type | example (JSON) | info | +=======+========+================+============================+ | name | string | "name": "cube" | available in all 3D | | | | | fileformats & scenes | +-------+--------+----------------+----------------------------+ | class | string | "class": | available through custom | van Kammen Expires 7 March 2024 [Page 4] Internet-Draft XR Fragments September 2023 | | | "cubes" | property in 3D fileformats | +-------+--------+----------------+----------------------------+ | href | string | "href": | available through custom | | | | "b.gltf" | property in 3D fileformats | +-------+--------+----------------+----------------------------+ | src | string | "src": | available through custom | | | | "#q=cube" | property in 3D fileformats | +-------+--------+----------------+----------------------------+ Table 3 Popular compatible 3D fileformats: .gltf, .obj, .fbx, .usdz, .json (THREEjs), COLLADA and so on. | NOTE: XR Fragments are file-agnostic, which means that the | metadata exist in programmatic 3D scene(nodes) too. 6. Navigating 3D Here's an ascii representation of a 3D scene-graph which contains 3D objects ◻ and their metadata: +--------------------------------------------------------+ | | | index.gltf | | │ | | ├── ◻ buttonA | | │ └ href: #pos=1,0,1&t=100,200 | | │ | | └── ◻ buttonB | | └ href: other.fbx | <-- file-agnostic (can be .gltf .obj etc) | | +--------------------------------------------------------+ An XR Fragment-compatible browser viewing this scene, allows the end- user to interact with the buttonA and buttonB. In case of buttonA the end-user will be teleported to another location and time in the *current loaded scene*, but buttonB will *replace the current scene* with a new one (other.fbx). 7. Embedding 3D content Here's an ascii representation of a 3D scene-graph with 3D objects (◻) which embeds remote & local 3D objects (◻) (without) using queries: van Kammen Expires 7 March 2024 [Page 5] Internet-Draft XR Fragments September 2023 +--------------------------------------------------------+ +-------------------------+ | | | | | index.gltf | | ocean.com/aquarium.fbx | | │ | | │ | | ├── ◻ canvas | | └── ◻ fishbowl | | │ └ src: painting.png | | ├─ ◻ bass | | │ | | └─ ◻ tuna | | ├── ◻ aquariumcube | | | | │ └ src: ://rescue.com/fish.gltf#q=bass%20tuna | +-------------------------+ | │ | | ├── ◻ bedroom | | │ └ src: #q=canvas | | │ | | └── ◻ livingroom | | └ src: #q=canvas | | | +--------------------------------------------------------+ An XR Fragment-compatible browser viewing this scene, lazy-loads and projects painting.png onto the (plane) object called canvas (which is copy-instanced in the bed and livingroom). Also, after lazy-loading ocean.com/aquarium.gltf, only the queried objects bass and tuna will be instanced inside aquariumcube. Resizing will be happen accordingly to its placeholder object (aquariumcube), see chapter Scaling. 8. Text in XR (tagging,linking to spatial objects) We still think and speak in simple text, not in HTML or RDF. It would be funny when people would shout

FIRE!

in case of emergency. Given the myriad of new (non-keyboard) XR interfaces, keeping text as is (not obscuring with markup) is preferred. Ideally metadata must come *later with* text, but not *obfuscate* the text, or *in another* file. | Humans first, machines (AI) later. This way: 1. XR Fragments allows hasslefree XR text tagging, using BibTeX metadata *at the end of content* (like visual-meta (https://visual.meta.info)). 2. XR Fragments allows hasslefree textual tagging, spatial tagging, and supra tagging, by mapping 3D/text object (class)names to BibTeX van Kammen Expires 7 March 2024 [Page 6] Internet-Draft XR Fragments September 2023 3. inline BibTeX is the minimum required *requestless metadata*- layer for XR text, RDF/JSON is great but optional (and too verbose for the spec-usecases). 4. Default font (unless specified otherwise) is a modern monospace font, for maximized tabular expressiveness (see the core principle (#core-principle)). 5. anti-pattern: hardcoupling a mandatory *obtrusive markuplanguage* or framework with an XR browsers (HTML/VRML/Javascript) (see the core principle (#core-principle)) 6. anti-pattern: limiting human introspection, by immediately funneling human thought into typesafe, precise, pre-categorized metadata like RDF (see the core principle (#core-principle)) This allows recursive connections between text itself, as well as 3D objects and vice versa, using *BiBTeX-tags* : +--------------------------------------------------+ | My Notes | | | | The houses seen here are built in baroque style. | | | | @house{houses, <----- XR Fragment triple/tag: tiny & phrase-matching BiBTeX | url = {#.house} <------------------- XR Fragment URI | } | +--------------------------------------------------+ This sets up the following associations in the scene: 1. textual tag: text or spatial- occurences named 'houses' is now automatically tagged with 'house' 2. spatial tag: spatial object(s) with class:house (#.house) is now automatically tagged with 'house' 3. supra-tag: text- or spatial-object named 'house' (spatially) elsewhere, is now automatically tagged with 'house' Spatial wires can be rendered, words can be highlighted, spatial objects can be highlighted, links can be manipulated by the user. | The simplicity of appending BibTeX (humans first, machines later) | is demonstrated by visual-meta (https://visual-meta.info) in | greater detail, and makes it perfect for GUI's to generate | (bib)text later. Humans can still view/edit the metadata | manually, by clicking 'toggle metadata' on the 'back' (contextmenu | e.g.) of any XR text, anywhere anytime. van Kammen Expires 7 March 2024 [Page 7] Internet-Draft XR Fragments September 2023 8.1. Default Data URI mimetype The src-values work as expected (respecting mime-types), however: The XR Fragment specification bumps the traditional default browser- mimetype text/plain;charset=US-ASCII to a green eco-friendly: text/plain;charset=utf-8;bibtex=^@ This indicates that any bibtex metadata starting with @ will automatically get filtered out and: * automatically detects textual links between textual and spatial objects It's concept is similar to literate programming. Its implications are that local/remote responses can now: * (de)multiplex/repair human text and requestless metadata (see the core principle (#core-principle)) * no separated implementation/network-overhead for metadata (see the core principle (#core-principle)) * ensuring high FPS: HTML/RDF historically is too 'requesty' for game studios * rich send/receive/copy-paste everywhere by default, metadata being retained (see the core principle (#core-principle)) * less network requests, therefore less webservices, therefore less servers, and overall better FPS in XR | This significantly expands expressiveness and portability of human | text, by *postponing machine-concerns to the end of the human | text* in contrast to literal interweaving of content and | markupsymbols (or extra network requests, webservices e.g.). For all other purposes, regular mimetypes can be used (but are not required by the spec). To keep XR Fragments a lightweight spec, BiBTeX is used for text- spatial object mappings (not a scripting language or RDF e.g.). | Applications are also free to attach any JSON(LD / RDF) to spatial | objects using custom properties (but is not interpreted by this | spec). van Kammen Expires 7 March 2024 [Page 8] Internet-Draft XR Fragments September 2023 8.2. URL and Data URI +--------------------------------------------------------------+ +------------------------+ | | | author.com/article.txt | | index.gltf | +------------------------+ | │ | | | | ├── ◻ article_canvas | | Hello friends. | | │ └ src: ://author.com/article.txt | | | | │ | | @friend{friends | | └── ◻ note_canvas | | ... | | └ src:`data:welcome human @...` | | } | | | +------------------------+ | | +--------------------------------------------------------------+ The enduser will only see welcome human and Hello friends rendered spatially. The beauty is that text (AND visual-meta) in Data URI promotes rich copy-paste. In both cases, the text gets rendered immediately (onto a plane geometry, hence the name '_canvas'). The XR Fragment-compatible browser can let the enduser access visual- meta(data)-fields after interacting with the object (contextmenu e.g.). The mapping between 3D objects and text (src-data) is simple: Example: +------------------------------------------------------------------------------------+ | | | index.gltf | | │ | | └── ◻ rentalhouse | | └ class: house | | └ ◻ note | | └ src:`data: todo: call owner | | @house{owner, | | url = {#.house} | | }` | +------------------------------------------------------------------------------------+ Attaching visualmeta as src metadata to the (root) scene-node hints the XR Fragment browser. 3D object names and classes map to name of visual-meta glossary-entries. This allows rich interaction and interlinking between text and 3D objects: 1. When the user surfs to https://.../index.gltf#AI the XR Fragments-parser points the enduser to the AI object, and can show contextual info about it. van Kammen Expires 7 March 2024 [Page 9] Internet-Draft XR Fragments September 2023 2. When (partial) remote content is embedded thru XR Fragment queries (see XR Fragment queries), its related visual-meta can be embedded along. 8.3. BibTeX as lowest common denominator for tagging/triple The everything-is-text focus of BiBTex is a great advantage for introspection, and perhaps a necessary bridge towards RDF (extrospective). BibTeX-appendices (visual-meta e.g.) are already adopted in the physical world (academic books), perhaps due to its terseness & simplicity: 1. frictionless copy/pasting (by humans) of (unobtrusive) content AND metadata 2. an introspective 'sketchpad' for metadata, which can (optionally) mature into RDF later +====================+==========================+=================+ | characteristic | Plain Text (with BibTeX) | RDF | +====================+==========================+=================+ | perspective | introspective | extrospective | +--------------------+--------------------------+-----------------+ | space/scope | local | world | +--------------------+--------------------------+-----------------+ | everything is text | yes | no | | (string) | | | +--------------------+--------------------------+-----------------+ | leaves (dictated) | yes | no | | text intact | | | +--------------------+--------------------------+-----------------+ | markup language(s) | no (appendix) | ~4 different | +--------------------+--------------------------+-----------------+ | polyglot format | no | yes | +--------------------+--------------------------+-----------------+ | easy to copy/paste | yes | depends | | content+metadata | | | +--------------------+--------------------------+-----------------+ | easy to write/ | yes | depends | | repair | | | +--------------------+--------------------------+-----------------+ | easy to parse | yes (fits on A4 paper) | depends | +--------------------+--------------------------+-----------------+ | infrastructure | selfcontained (plain | (semi)networked | | storage | text) | | +--------------------+--------------------------+-----------------+ | tagging | yes | yes | +--------------------+--------------------------+-----------------+ | freeform tagging/ | yes | depends | van Kammen Expires 7 March 2024 [Page 10] Internet-Draft XR Fragments September 2023 | notes | | | +--------------------+--------------------------+-----------------+ | specialized file- | no | yes | | type | | | +--------------------+--------------------------+-----------------+ | copy-paste | yes | depends | | preserves metadata | | | +--------------------+--------------------------+-----------------+ | emoji | yes | depends | +--------------------+--------------------------+-----------------+ | predicates | free | pre-determined | +--------------------+--------------------------+-----------------+ | implementation/ | no | depends | | network overhead | | | +--------------------+--------------------------+-----------------+ | used in (physical) | yes (visual-meta) | no | | books/PDF | | | +--------------------+--------------------------+-----------------+ | terse categoryless | yes | no | | predicates | | | +--------------------+--------------------------+-----------------+ | nested structures | no | yes | +--------------------+--------------------------+-----------------+ Table 4 | To serve humans first, human 'fuzzy symbolical mind' comes first, | and 'categorized typesafe RDF hive mind' | (https://en.wikipedia.org/wiki/Borg)) later. 8.4. XR text (BibTeX) example parser Here's a naive XR Text (de)multiplexer in javascript (which also supports visual-meta start/end-blocks): xrtext = { decode: { text: (str) => { let meta={}, text='', last='', data = ''; str.split(/\r?\n/).map( (line) => { if( !data ) data = last === '' && line.match(/^@/) ? line[0] : '' if( data ){ if( line === '' ){ xrtext.decode.bibtex(data.substr(1),meta) data='' }else data += `${line}\n` } van Kammen Expires 7 March 2024 [Page 11] Internet-Draft XR Fragments September 2023 text += data ? '' : `${line}\n` last=line }) return {text, meta} }, bibtex: (str,meta) => { let st = [meta] str .split(/\r?\n/ ) .map( s => s.trim() ).join("\n") // be nice .replace( /}@/, "}\n@" ) // to authors .replace( /},}/, "},\n}" ) // which struggle .replace( /^}/, "\n}" ) // with writing single-line BiBTeX .split( /\n/ ) // .filter( c => c.trim() ) // actual processing: .map( (s) => { if( s.match(/(^}|-end})/) && st.length > 1 ) st.shift() else if( s.match(/^@/) ) st.unshift( st[0][ s.replace(/(-start|,)/g,'') ] = {} ) else s.replace( /(\w+)\s*=\s*{(.*)}(,)?/g, (m,k,v) => st[0][k] = v ) }) return meta } }, encode: (text,meta) => { if( text === false ){ if (typeof meta === "object") { return Object.keys(meta).map(k => typeof meta[k] == "string" ? ` ${k} = {${meta[k]}},` : `${ k.match(/[}{]$/) ? k.replace('}','-start}') : `${k},` }\n` + `${ xrtext.encode( false, meta[k])}\n` + `${ k.match(/}$/) ? k.replace('}','-end}') : '}' }\n` .split("\n").filter( s => s.trim() ).join("\n") ) .join("\n") } return meta.toString(); }else return `${text}\n${xrtext.encode(false,meta)}` } } var {meta,text} = xrtext.decode.text(str) // demultiplex text & bibtex meta['@foo{'] = { "note":"note from the user"} // edit metadata xrtext.encode(text,meta) // multiplex text & bibtex back together van Kammen Expires 7 March 2024 [Page 12] Internet-Draft XR Fragments September 2023 | above can be used as a startingpoint for LLVM's to translate/ | steelman to any language. 9. HYPER copy/paste The previous example, offers something exciting compared to simple copy/paste of 3D objects or text. XR Fragment allows HYPER-copy/ paste: time, space and text interlinked. Therefore, the enduser in an XR Fragment-compatible browser can copy/paste/share data in these ways: * time/space: 3D object (current animation-loop) * text: TeXt object (including BiBTeX/visual-meta if any) * interlinked: Collected objects by visual-meta tag 10. XR Fragment queries Include, exclude, hide/shows objects using space-separated strings: * #q=cube * #q=cube -ball_inside_cube * #q=* -sky * #q=-.language .english * #q=cube&rot=0,90,0 * #q=price:>2 price:<5 It's simple but powerful syntax which allows css-like class/ id-selectors with a searchengine prompt-style feeling: 1. queries are only executed when embedded in the asset/scene (thru src). This is to prevent sharing of scene-tampered URL's. 2. search words are matched against 3D object names or metadata- key(values) 3. # equals #q=* 4. words starting with . (.language) indicate class-properties | *(*For example**: #q=.foo is a shorthand for #q=class:foo, which | will select objects with custom property class:foo. Just a simple | #q=cube will simply select an object named cube. * see an example video here (https://coderofsalvation.github.io/xrfragment.media/queries.mp4) van Kammen Expires 7 March 2024 [Page 13] Internet-Draft XR Fragments September 2023 10.1. including/excluding |''operator'' | ''info'' | |* | select all objects (only allowed in src custom property) in the current scene (after the default [[predefined_view|predefined_view]] # was executed)| |- | removes/hides object(s) | |: | indicates an object-embedded custom property key/value | |. | alias for class: (.foo equals class:foo | |> <| compare float or int number| |/ | reference to root-scene. Useful in case of (preventing) showing/hiding objects in nested scenes (instanced by [[src]]) #q=-/cube hides object cube only in the root-scene (not nested cube objects) #q=-cube hides both object cube in the root-scene AND nested skybox objects | » example implementation (https://github.com/coderofsalvation/xrfragment/blob/main/src/3rd/js/ three/xrf/q.js) » example 3D asset (https://github.com/coderofsalvation/xrfragment/blob/main/example/ assets/query.gltf#L192) » discussion (https://github.com/coderofsalvation/xrfragment/issues/3) 10.2. Query Parser Here's how to write a query parser: 1. create an associative array/object to store query-arguments as objects 2. detect object id's & properties foo:1 and foo (reference regex: /^.*:[><=!]?/ ) 3. detect excluders like -foo,-foo:1,-.foo,-/foo (reference regex: /^-/ ) 4. detect root selectors like /foo (reference regex: /^[-]?\// ) 5. detect class selectors like .foo (reference regex: /^[-]?class$/ ) 6. detect number values like foo:1 (reference regex: /^[0-9\.]+$/ ) 7. expand aliases like .foo into class:foo 8. for every query token split string on : 9. create an empty array rules 10. then strip key-operator: convert "-foo" into "foo" 11. add operator and value to rule-array 12. therefore we we set id to true or false (false=excluder -) 13. and we set root to true or false (true=/ root selector is present) 14. we convert key '/foo' into 'foo' 15. finally we add the key/value to the store (store.foo = {id:false,root:true} e.g.) van Kammen Expires 7 March 2024 [Page 14] Internet-Draft XR Fragments September 2023 | An example query-parser (which compiles to many languages) can be | found here | (https://github.com/coderofsalvation/xrfragment/blob/main/src/ | xrfragment/Query.hx) 10.3. XR Fragment URI Grammar reserved = gen-delims / sub-delims gen-delims = "#" / "&" sub-delims = "," / "=" | Example: ://foo.com/my3d.gltf#pos=1,0,0&prio=-5&t=0,100 +=============================+=================================+ | Demo | Explanation | +=============================+=================================+ | pos=1,2,3 | vector/coordinate argument e.g. | +-----------------------------+---------------------------------+ | pos=1,2,3&rot=0,90,0&q=.foo | combinators | +-----------------------------+---------------------------------+ Table 5 11. Security Considerations Since XR Text contains metadata too, the user should be able to set up tagging-rules, so the copy-paste feature can : * filter out sensitive data when copy/pasting (XR text with class:secret e.g.) 12. IANA Considerations This document has no IANA actions. 13. Acknowledgments TODO acknowledge. van Kammen Expires 7 March 2024 [Page 15]