n0 XML property registry

Status: Design inventory; companion to the n0 XML Draft 0 RFD.

Later-version reuse vocabulary is specified by the modules and static component reuse, component parameters, and component slots RFDs. Those rows remain Design until their language versions are accepted; Draft 0 continues to reject them.

The durable-addressing RFD accepts a Version 4 identity and typed effective-value boundary. Version 4 inherits the earlier component vocabulary, but it does not change which rows Draft 0 accepts and does not make a registered property animatable.

This page is the canonical inventory of XML-facing property names and their valid targets. It is not, by itself, a grammar extension. Only rows marked Draft 0 are accepted by a Draft 0 reader. Placeholder and Design rows remain invalid until a later, versioned n0 XML specification defines their complete syntax and semantics.

Before this registry, Grida had two related documents but no complete XML applicability crosswalk:

• Grida IR inventories the production scene model.
• n0 XML defines the small normative Draft 0 authored language.

This registry connects those views without making the XML spelling mirror implementation field names.

Grounding and precedence

This inventory was reconciled against the canonical scene model and the packed archive contract. The scene model is the source of truth for representable scene semantics; archive coverage separately determines what .grida can persist. Differences between those contracts are recorded below rather than being averaged into a third model.

Draft 0's repeatable stroke geometry is the one accepted extension beyond that current production model. It reuses the existing stroke geometry plus Paints pair but requires the production engine and archive to own an ordered list of those pairs; the seam is recorded explicitly below.

For paths, the existing contracts do not present one uniform model: one form stores raw coordinates and derives intrinsic geometry, while another defines a canonical shape mapped into a layout box. Draft 0 selects the latter and fixes its reference rectangle to 0 0 1 1. This is an explicit compatibility choice, not an attempt to average the two forms or hide a raw-path conversion behind XML-only state.

n0 XML projects that model as an authored language:

1. XML uses familiar, semantic names when CSS, SVG, HTML, or Flutter already provide one.
2. When those vocabularies have no equivalent, an established design, motion, or photo-tool term is preferable to a Grida-only invention.
3. Multi-word names use kebab-case.
4. Element names carry the primary type. The bounded gradient family alone uses kind to select one of its structurally shared production variants; a generic paint or render-node kind does not exist.
5. Tree nesting carries parenthood and painter order; parent, children, and archive ordering fields are not authored properties.
6. Resolved bounds, glyph runs, vector materializations, caches, and transient runtime identifiers are derived data, not XML properties.
7. One meaning gets one canonical writer spelling. A compact form may own a deliberately disjoint canonical domain, as fill="#RRGGBB" does for one ordinary solid; it never combines with the expanded channel.

Status key

Placeholder rows are deliberately non-operative. A Draft 0 reader must still diagnose them as unknown syntax.

Element inventory

The table covers the production node set as well as XML-only source constructs. “Children” means render-node children, not typed property children such as fill, stroke, or gradient stop elements. “Assigned” means Version 3 direct render roots projected to a component declaration rather than ordinary children owned by use. tspan and slot are listed explicitly as contextual source constructs even though neither is a scene node.

Attributed text remains one <text> node with direct, flat <tspan> children. tspan contains exact character data plus an optional literal-first fill property; it has no scene identity, box, transform, opacity, layout, or render children. <span> is not an alias and a reader must never support both spellings.

Draft 0 attribute registry

This is the compact applicability index for syntax already defined by the Draft 0 RFD. The RFD remains normative for value grammar, defaults, contradictions, and resolution behavior.

font-size, font-weight, and font-style default on text to 16, 400, and normal. The same attributes on tspan override the owning text default for that run; omission inherits from text, never a preceding run. size and a generic style attribute are not n0 XML spellings.

The rounded box geometry contract defines the exact grammar. In registry form, corner-radius is one or exactly four non-negative finite horizontal radii, optionally followed by / and an independent one-or-four-value vertical list. Four-value order is top-left, top-right, bottom-right, bottom-left. corner-smoothing is finite in [0, 1]. Both attributes default to zero and apply only to container and rect.

The canonical writer shortens an all-equal axis list to one value, otherwise emits all four; it omits the slash when every horizontal and vertical radius pair is equal. It omits zero defaults, but preserves nonzero smoothing with zero radii as dormant intent. Oversized ordinary radii use one edge-sum-based proportional factor; nonzero smoothing uses the production profile's per-corner half-short-side cap. Neither resolved form is rewritten in source.

For path, d is required and uses the complete SVG path-data grammar in a fixed 0 0 1 1 reference rectangle. Validation is against exact tight curve geometry, which must stay within the closed unit box. The geometry maps nonuniformly to the resolved declared box before fill and stroke construction; it is never measured or tight-fitted. fill-rule defaults to nonzero and also accepts evenodd. Paints use the full resolved box, children remain box-local and unclipped, and the default fill is black. Path strokes accept only scalar width; center is the default and is required whenever any contour is open. Resolution maps the command stream once; bounds and all paint channels consume that exact mapped geometry. Numeric unrepresentability is a resolution failure, never permission to clamp, substitute the declared box, or retain partial path ink.

Proposed later-version module vocabulary

The module and component RFD proposes this source-only vocabulary. These rows are not operative Draft 0 grammar.

Component definitions precede an optional one-container scene root. A source may therefore be a component library, a render entry, or both. Every component reference requires an explicit fragment, including local references such as href="#button"; there is no default component export or implicit scene-root export in the proposal.

use intentionally does not accept width, height, paints, opacity, transforms, or arbitrary component properties in the static Draft 1 proposal. The boxed definition owns those values. The component-parameter RFD proposes intentional scalar customization through prop/arg in Version 2; Version 1 continues to reject them.

Proposed Version 2 scalar parameter vocabulary

These rows summarize the component-parameter RFD. They remain non-operative design syntax until accepted and implemented.

Version 2 defines no universal null, expression language, or parameterized attribute presence. A use may contain arg property children but still may not contain render children. Version 3 projection is specified separately and does not backport slot declarations, assignment attributes, or render children into Version 2.

Proposed Version 3 named slot vocabulary

These rows summarize the component-slot RFD. They remain non-operative design syntax until accepted as a stable language version.

The slot assignment relationship is contextual source metadata, not an ordinary render property. It is invalid on a node outside the direct assignment position, is absent from the Draft 0 attribute registry, and never appears in the ordinary materialized scene. Version 3 has no wrapper, unnamed/default slot, fallback, requiredness, or explicit-empty form. Versions 0, 1, and 2 continue to reject all slot syntax.

Version 4 durable identity vocabulary

These rows summarize the accepted durable-addressing RFD. Version 4 inherits the complete Version 3 language but links only Version 4 component sources so every materialized authored node has a complete address.

Versions 0 through 3 do not accept this new render/use id syntax and never receive generated durable addresses.

Version 4 effective-value registry

Version 4 also fixes the node-level semantic properties that may enter one immutable effective-value evaluation. This is not new authored animation syntax and registration does not mean a property is animatable. A missing entry reads the materialized base value; optional states live inside the exact value type rather than a universal null.

Keys name model properties, not alternative source spellings. Compact and expanded fills both project fills; source hidden projects the inverse active value; the flex attributes collectively project one layout value.

Impact legend: M = measure, L = layout, T = transform, B = bounds, P = paint, and R = resource.

Rotation is any finite number. Growth is finite and non-negative. Opacity and corner smoothing are finite in [0, 1]. Fixed sizes and present constraints are finite and non-negative; a present aspect ratio contains two finite positive numbers. Aggregate layout, corner, fill, and stroke values retain all of their static nested and renderer-capability validation. Cross-property rules are checked against the complete effective node state, so an otherwise valid replacement cannot combine with an authored value to create a state the renderer would silently omit. Keys with R impact may select logical resources but never perform loading; resource readiness and bytes belong to a separately revisioned evaluation environment. The exact addressing, applicability, nullability, validation, and static-equivalence laws are normative in n0 XML durable addressing.

Scene-backed property placeholders

These tables reserve discussion slots for properties in the canonical scene model. They do not claim the proposed XML spelling is final.

Identity, compositing, transform, and box geometry

Version 4 id maps to durable authored identity, not the runtime's transient node handle. It is required, literal, lowercase-kebab, and unique within its scene or component owner. The same Version 4 spelling on use identifies the caller-owned occurrence; the component export id remains a separate module-local symbol. Component roots use the distinguished root-member identity rather than a second attribute. The exact address and occurrence-path contract is defined by n0 XML durable addressing.

transform also cannot be admitted until its relationship to native rotation, flip-x, flip-y, and lens ops has one canonical answer. Versions 0 through 3 continue to reject id on render nodes and use.

Primitive geometry

The runtime currently calls the ellipse extent angle; sweep-angle is the clearer authored candidate because it states what the number means. Draft 0 already uses SVG's established d name for box-mapped path commands rather than exposing a storage-oriented data name.

view-box remains deferred. If introduced, it would let imported coordinates retain a stable non-unit reference rectangle, but that rectangle must be authored intent with positive extents and must never be re-derived from path tight bounds after an edit. Its omission, canonical writer behavior, and interaction with the fixed unit form need one versioned rule before the attribute can be accepted.

Scene image

Resource declaration, packaging, network policy, intrinsic size, and missing resource behavior must be shared by scene images and image paints. The same src must not acquire unrelated identity semantics merely because its image appears in a different context.

Structural property elements

Some production properties are ordered or structured values and should remain XML children rather than become mini-languages inside attributes.

Paint attribute registry

These paint attributes are already normative in Draft 0. Their semantics are defined in the paint channels section.

opacity is contextual: on a gradient or image it remains a floating-point paint property, while on solid and stop it materializes through color alpha as described by the RFD's quantization rule.

A gradient transform must be finite and mathematically invertible. Linear endpoints remain valid outside the unit box, but after centered-alignment lowering their binary32 unit-space distance must be greater than 2^-15; shorter ramps are rejected rather than silently narrowed to the backend's degenerate-color fallback. The same authored-state checks apply to source, canonical writing, and a replacement Paints value.

This does not promise that every transform is numerically invertible after a particular resolved paint box is composed in a raster backend. Evaluation must check that exact composed matrix and construct the selected gradient implementation before publishing the frame. Extremely small or large values can be accepted here yet fail for one box and succeed for another; such a failure is contextual frame evaluation, not source repair or a second paint- validity rule.

Stroke geometry attribute registry

Each stroke is one geometry with direct typed paint children. An empty paint list is valid only when at least one geometry value differs from the target's defaults. These scoped attributes are normative in Draft 0:

The production model already separates one stroke Paints stack from one stroke geometry. One XML stroke, using only attributes supported by its target, projects that pair directly. A default empty pair canonicalizes to omission; non-default empty geometry remains explicit. Repeatable stroke elements are an accepted extension to an ordered list of those pairs; the current production model still needs that multiplicity before it can materialize more than one without loss.

Per-side width grammar

One width number selects uniform stroke width. Exactly four numbers select rectangular widths in top, right, bottom, left order and are valid only for a container or rect. Two- and three-number expansion, commas, units, negative values, and non-finite values are invalid. The omitted default is uniform 1.

Four equal positive values normalize to the uniform state; four zeros and a scalar zero normalize to the no-width state. A canonical writer omits uniform 1, uses one number for every other uniform or no-width state, and writes all four values only when they differ. Applicability is validated before this normalization, so four values remain invalid on an ellipse, line, path, or text even when equal.

The four local-side widths produce one outer-minus-inner coverage ring with one shared ordered paint stack. inside, center, and outside use outward and inward fractions (0, 1), (1/2, 1/2), and (1, 0), respectively. Each corner's outer radius adds the outward fraction of its adjacent horizontal and vertical widths; its inner radius subtracts the inward fractions and clamps each result to zero. A zero or negative inner-box extent makes the inner contour empty, saturating coverage to the outer contour without rewriting source widths.

Ordinary circular and elliptical corner radii and continuous dash-array traversal remain valid. A zero-width side has no coverage but still advances the dash metric. Per-side widths currently require zero corner smoothing, join="miter", and miter-limit="4"; other combinations are rejected rather than accepted as state the rectangular renderer cannot honor.

Deferred stroke geometry

Variable-width profiles need structured grammar of their own and should not be forced into an opaque comma-separated attribute merely to look CSS-like.

Text attributes and property placeholders

text owns the paragraph, default text style, and node paints. A direct, flat tspan is only a contextual run and inherits every omitted run property from the owning text, not from its preceding sibling. Draft 0 uses explicit kebab-case attributes and defines no style mini-language.

This registry inventories authored XML properties only. The Universal Shaped Text Layout RFD owns their eventual shaping, font resolution, line construction, UTF-8 mapping, metrics, and resolved bounds; adding a property here must project into that one resolution contract, not create a second measurement or rendering path.

The Draft 0 defaults are font-size="16", font-weight="400", and font-style="normal". size is invalid and is never accepted alongside or as an alias for font-size; a canonical writer omits all three defaults on text. Every other style row above remains unknown syntax until its status advances; production defaults supply those unexposed TextStyleRec fields during materialization.

Character data and direct tspan data concatenate in document order into one production AttributedString. Run boundaries are derived as UTF-8 byte offsets; authors do not spell them. Runs cover the entire string contiguously and merge when complete style and paint-override state match. Empty tspan is invalid, while an empty text uses the production 0..0 default-run special case.

Run fills project StyledTextRun.fills rather than a parallel color field. Omitted run fill maps to None and node-fill fallback. The fill attribute maps to an explicit one-solid stack. A singular literal-first <fill> child uses the existing ordered paint grammar; <fill/> maps to an explicit empty stack, and non-empty typed children remain bottom-to-top. Attribute and child are mutually exclusive. Gradient and image coordinates use the resolved full text-node paint box, never a per-tspan fragment box.

HTML tags (b, strong, i, em, and similar), <span>, and SVG tspan positioning are intentionally not aliases. The production run model contains visual style, not the semantic/accessibility annotation needed to preserve HTML meaning, and Grida run geometry does not independently position chunks.

CSS vertical-align is intentionally not proposed for paragraph-box vertical placement: its web meaning concerns inline/baseline alignment. Flutter's textAlignVertical is the closer semantic precedent.

Effect placeholders

The canonical scene model includes one layer blur, one backdrop blur, one liquid-glass effect, multiple shadows, and multiple noise effects. Candidate typed names are familiar, but the container grammar is not yet decided.

An ordered <effects> list would be ergonomic, but the production model is not a single ordered heterogeneous list. The XML must not imply reorderable effect semantics until either the existing slots and lists receive a defined cross-type order or the engine model deliberately changes.

Syntax that needs dedicated design

These are not ordinary missing attributes. Each needs a focused RFD because its structure, identity, or evaluation rules cannot be made reliable by choosing a name alone.

The vector-network and width-profile grammars are the clearest examples of where new syntax must be invented. Treating either as a JSON-shaped data attribute would hide structure, weaken diagnostics, and make hand or LLM authoring less reliable.

Current scene-contract seams to reconcile

This registry does not itself change the canonical scene or archive contracts. The following seams constrain conformance or require the explicit extension named by the Draft 0 RFD:

When the language, runtime, and archive disagree, a processor must limit its claimed subset or make the model change explicit. It must never create a parallel XML-only property merely to conceal the incompatibility.