The master rung tracker: the HTML, CSS, and SVG surface as bare spec-vocabulary items, each checked when a Chromium-gated rung lands it on the n0 path.

Web checklist

One master tracker for the Web surface of the n0 path (websem → rframe → n0) — the SVG engine of record, with the HTML and CSS surface ahead of it — HTML, CSS, and SVG in one document, because the three share one cascade and half a vocabulary. Items only, in the platform's own words, enumerated from the external spec indexes linked at each section head — never from this tree. A box ticks only when a Chromium-gated rung lands the named construct at its full listed grammar — where cited references disagree, the standard-track grammar is the bar, and an experimental draft grammar does not raise it; a partial admission stays unchecked — the remaining grammar is remaining work, and a construct's finer-grained gaps live in their own rows (<rect> is landed; rx/ry are not). A row ticks only for its own section's index entry: an attribute spelling and its CSS property twin are separate rows, each ticked on its own docs-commit evidence. A rung's docs commit ticks its rows. To see what is done, open the visual corpus — semantics live in the statement of record, rung history in the D-N register, and no score is computed from this list (FLIP is unratified).

--*

CSS cascading and inheritance

all

display
order
visibility

page

image-orientation
image-rendering
object-fit
object-position

CSS shapes

shape-outside
shape-margin
shape-image-threshold

CSS masking

clip-path
clip-rule

2026-08-24 split: the URL/none part of clip-path now enters through the pinned cascade on non-root SVG targets, including presentation hints, inline style, stylesheets, the -webkit- alias, var(), and normal cascade precedence. The row stays open for basic shapes, geometry boxes, the root CSS-layer route, external and cyclic resources, and Chromium's raster-mask strategies. The clip-rule property stays open because this Servo-mode Stylo pin has no such longhand; its CSS ingresses are quarantined rather than matched outside the cascade. The presentation-attribute evidence is recorded below.

2026-08-24 split: same-document SVG image masks now render through the direct presentation-attribute route described below. Every CSS mask-family row remains open: this Servo-mode Stylo pin furnishes no computed mask route the compiler can consume, so authored declarations are quarantined by name across style attributes, stylesheets, shorthands, longhands, border longhands, and the -webkit-mask-image alias. No matcher was added around the cascade. mask-border-mode, present in CSS Masking Level 1, is added to the checklist here; it was missing from the earlier enumeration.

Filter effects

2026-08-25 split: same-document SVG resource filters now enter through the direct presentation-attribute route recorded below. The CSS filter row stays open: the pinned Servo-mode cascade represents filter functions but not the URL variant needed by an SVG resource, and function lists are a separate unresolved operation grammar. Authored declarations are therefore quarantined by name rather than matched by a second cascade. The other four filter-effect properties are Gecko-only at this Stylo pin and also remain open. The direct feFlood attribute route now carries an admitted subset, but it does not create a CSS computed-value route and does not change these property rows.

Compositing and blending

mix-blend-mode
background-blend-mode
isolation

ruby-align
ruby-overhang
ruby-position

CSS lists and counters

CSS generated content

content
quotes

overflow-anchor

CSS overscroll behavior

CSS scrollbars styling

scrollbar-color
scrollbar-width

view-transition-class
view-transition-name

touch-action

CSS containment and container queries

CSS will change

will-change

CSS viewport

zoom

MathML Core

math-depth
math-shift
math-style

CSS speech

speak

SVG presentation properties

cx
cy
r

2026-08-22 split: the CSS twins remain open at the pinned Stylo cap: this build has no cx/cy/r longhands, and both authored CSS ingresses are quarantined rather than matched outside the cascade. The attribute-rung evidence is recorded with the presentation-attribute rows below.

rx
ry
x
y

2026-08-22 split: the CSS x/y twins remain open at the pinned Stylo cap. Chromium honors both authored CSS ingresses (measured, not celled), while this build has no corresponding longhands; the ingresses now refuse by name rather than painting the attribute position. The attribute-rung evidence is recorded below.

2026-08-23 split: the CSS property remains open at the pinned Stylo cap: this build has no d longhand, and the stylesheet and inline-style ingresses remain quarantined by name rather than matched outside the cascade. The presentation attribute closes independently below.

Sources: the SVG 2 element index, attribute index, and property index — including the Filter Effects primitives and the SMIL animation elements the element index carries — plus the MDN SVG attribute reference for attributes the platform ships ahead of the SVG 2 indexes.

SVG elements

2026-08-24 split: direct admitted geometry and <use> contributors now form Chromium-gated path unions, and chained resources form intersections. The element stays open because visible text, a child carrying its own clip, animation, and the 43-or-more-contributor route switch Chromium to a raster mask that the resolved contract deliberately cannot express.

2026-08-25 split: the static filter graph carries safe-kernel feGaussianBlur operations over SourceGraphic, SourceAlpha, a prior result, or a resolved result name. It includes same-document first-id lookup, quoted and unquoted forms of a single URL token, both coordinate systems, hard effect and primitive regions, both filter color spaces, transforms, <use>, stroke, nesting, and the established filter-before-mask-before-opacity-before-clip order. Both element rows stay open: <filter> still has the rest of the primitive family, inheritance, multi-operation lists, host, and dynamics surface; <feGaussianBlur> still has valid empty primitive results, inherited raw-syntax gaps, animation, and a measured small-kernel backend precision boundary. Current Chromium drops every edgeMode spelling on this primitive (measured, not celled), but that attribute also applies to <feConvolveMatrix> and stays open. 2026-08-25 close/split: feFlood, feComposite, feMerge, and feMergeNode now carry the complete static primitive behavior for their rows: zero-, two-, and ordered N-input graph nodes; all seven composite operators; arithmetic coefficients; input/result routing; hard primitive regions; color-space placement; and the crisp compositional shadow graph. feOffset carries integer displacement, both unit systems, signed values, regions, and graph routing, but stays open. Valid fractional displacements differ at 48 pixels / maximum delta 128, and every sampled graph combining blur with offset differs at a second backend boundary; all such graphs conservatively refuse by stable name. Integer source offsets that target mapping turns fractional differ by 12–97 pixels, up to maximum delta 122; that mapped class has its own stable refusal too (measured, not celled). The earlier depth diagnosis is withdrawn: three safe-sigma blurs are exact, directly and through identity merges. Sampled effective sigmas from .5 through 1.875 differ while .25 and 2 are exact; the patrol conservatively refuses the open interval between those exact endpoints after target mapping (measured, not celled). It keeps <feGaussianBlur> open. A final opacity-normalization audit found one more silent class before close: raw f32 parse-then-divide selected the lower neighbour for 57.384267578125007%, changing all 4,096 amplified pixels at maximum delta 16. The direct decoder now keeps the CSS token's divide-then-narrow order, and one exact cell distinguishes the route. Sixty exact cells carry the shadow-graph rung. One additional review cell proves that a zero-sigma blur still applies its explicit primitive region; bypassing that crop changes 1,160 pixels at maximum delta 218. Hosted x86 verification also exposed seven composite/merge departures of one code value. Keeping generated-source byte rounding distinct from source-image floating coverage fixes six. The seventh is a one-input merge, so it has no internal composition stage on which that rule can run. The final layer restore now makes the same distinction: generated-only results use exact byte-domain SrcOver, while source-derived coverage stays floating. Together those boundaries restore exact output on both processor families without tolerance.

2026-08-25 close/split: <feDropShadow> now carries its complete static primitive behavior through one native, checked, one-input operation. Missing dx, dy, and stdDeviation use 2; the measured number-list grammar, independent negative-axis clamp, source and result routing, both primitive unit systems, hard regions, direct flood values, admitted sRGB placement, transforms, viewBox, <use>, stroke, groups, target opacity, clips, and neighboring admitted graph operations are covered by twenty-eight exact Chromium cells. A default-linear endpoint-color cell also consumes an earlier blur. The native operation includes its source foreground and is not rewritten into the separately guarded blur-plus-offset graph. Hosted processor-family verification first found all twenty-eight cells departing through the backend's direct helper, by as much as eight code values. Making the shadow's internal byte-domain compositions exact narrowed that to twenty-five source-derived sRGB cells, all at one code value; replacing the internal colorization and changing offset sampling left that exact set unchanged, and a zero-blur member was still in it. The remaining operation was the filtered layer's restore onto its backdrop. Exact byte-domain restore for sRGB native- shadow descendants makes both processor families exact without tolerance; applying that rule to every source-derived filter instead changes three unrelated floating-path cells, so color-space conversion clears it and the default-linear endpoint stays on the floating route. This is painter policy: the resolved contract remains one native operation. Four new refusal rows name native-shadow range, transform, source-layer, and linearRGB color-conversion precision boundaries; the shared small-kernel and flood cascade/value patrols also apply. Those independently registered boundaries leave dx, dy, stdDeviation, flood-color, flood-opacity, color-interpolation-filters, filter, and <filter> open for their wider applicability or value surface. Only the element row closes. The corpus is 475 Chromium-baked cells plus 10 sampled frames; the refusal register has 128 rows.

2026-08-25 close/split: <feColorMatrix> now carries its complete static primitive behavior as one checked one-input, non-premultiplied RGBA matrix. Missing and invalid type use matrix; all four case-sensitive members (matrix, saturate, hueRotate, luminanceToAlpha) are covered. The complete measured SVG number-list grammar, exact value counts and pass-through fallbacks, unclamped saturation, Blink-ordered large-angle hue arithmetic, ignored luminance values, channel crossing, alpha scaling and creation, output clamping, source/result routing, generated input, both color spaces, safe transforms, target opacity and clips are carried by twenty-seven exact Chromium cells. A fresh direct-shape probe corrected the earlier enum reading before close: wrong-case and surrounding-whitespace spellings are invalid and therefore select the default matrix behavior; surrounding whitespace does not make hueRotate valid. Three new refusal rows quarantine the measured source-layer, non-quarter-transform, and blur/shadow-composition precision boundaries. Their conservative safe envelope over-refuses some exact sources rather than releasing wrong edge pixels. The generic type, values, in, result, region, color-interpolation-filters, filter, and <filter> rows remain open for their wider applicability, cascade, resource, or dynamics surface. Only the element row closes. The corpus is 502 Chromium-baked cells plus 10 sampled frames; the refusal register has 131 rows.

2026-08-24 split: one isolated alpha/luminance source image, both coordinate systems, hard regions, admitted graphics children, transforms, gradients, clips, <use>, nesting, and target opacity now render. The element stays open because valid nested cycles and source children whose own element rows remain open still refuse transactionally; the root host-layer and external-resource routes remain separate boundaries. An unrepresented inline declaration on the resource also refuses before its inherited effect can change a source descendant silently.

SVG presentation attributes

2026-08-24 split: the clip-path presentation hint carries computed none and same-document url(#…) through the one cascade on admitted non-root SVG targets. Eight Chromium cells cover CSS ingress and precedence, first-id lookup, invalid references, geometric unions, inherited fill rules, both clip coordinate systems, transforms, viewBox, groups, <use>, stroke boxes, resource chains, and opacity ordering. Its basic-shape, geometry-box, root, external/cyclic, animation, and raster-mask branches remain registered refusals, so the row stays open. The direct inherited clip-rule route admits nonzero/evenodd and CSS-wide behavior, but valid comments, escapes, and var() still need the unavailable cascade longhand and refuse by name; that row also stays open.

2026-08-22 split: five Chromium-baked cells now cover the admitted cx/cy/r number/percentage route on <circle> and <ellipse>, including defaults, negative centers, invalid/zero radius, axis and normalized-diagonal bases, viewBox, <use>, transforms, and stroke. The three rows remain open: valid authored decimals can lose Chromium rounding provenance in the raw f32 route, finite sources can cross the unimplemented Chromium used-range split, CSS comments in otherwise numeric values still refuse, and the registered guards name all of those gaps before a non-finite frame or silent backend drop. Unit values, CSS math, var(), and CSS-wide keywords retain their own unchecked value-type rows.

2026-08-23 close: the complete none | <path-data> attribute grammar is Chromium-baked. Erroneous data now retains every complete segment before the error, including completed implicit repeats, while an error before a complete leading moveto is the correct empty geometry. Two source-number witnesses pin Blink's ordered float evaluation in both rounding directions; the same repair is independently celled for the shared polygon/polyline scanner. Extreme finite construction follows the browser's split between an invalid whole path and an arc that appends no segment while preserving the prior prefix. Seven new exact cells carry those branches; the three former path-data refusal rows graduate. The CSS d property twin stays open under the split above.

2026-08-25 split: the direct presentation attribute carries none, CSS-wide reset values, and one same-document URL token with quoted or unquoted content on admitted non-root SVG targets. Committed cells cover comments around the URL, first-id lookup, missing/wrong/malformed-reference fallback, groups, <use>, transforms, stroke, clip/mask/opacity ordering, and nesting. The row stays open for filter functions and lists, var(), inheritance, CSS precedence, root and external host routes, resource href, the measured small-kernel boundary, and the remaining primitives. The direct inherited color-interpolation-filters reader carries linearRGB, sRGB, auto, reset behavior, and inheritance for the admitted blur graph; CSS ingress, comments, escapes, and var() remain named gaps, and that row stays open too.

flood-color
flood-opacity

2026-08-25 split: direct attributes on feFlood now carry initial black/one, admitted sRGB colors and currentColor, number/percentage opacity with clamping, reset and invalid fallbacks, separate color-alpha × opacity multiplication, non-inheritance, and hard primitive regions. Both rows stay open for explicit inheritance, unavailable CSS ingress, and the independently listed wider color/math/custom-property value families; the native feDropShadow route reuses the admitted direct subset and the same named patrols.

2026-08-24 split: the mask presentation attribute admits none and one same-document url(#…), including CSS comments, first-id lookup, invalid-reference fallback, <use>, and nested-mask use. It stays open for the full shorthand/multiple-layer grammar, var(), root and external resource routes, cycles, unsupported source children, and the measured target-transform region-precision boundary. mask-type closes at its complete luminance | alpha grammar, including the missing/default value, invalid fallback, and reset keywords. Explicit inheritance and var() remain named refusals under their independently listed CSS-wide/custom-property rows; the CSS property twin stays open at the pinned-cascade boundary. A valid empty source always hides its target; opaque black hides in luminance mode and reveals under mask-type="alpha".

2026-08-22 split: the existing two rect-percentage basis cells plus three new grammar, <use>, and transform-plus-stroke cells cover the admitted finite number/percentage route for rect x/y/width/height, including defaults, negative coordinates, invalid non-positive extents, root units, viewBox, instances, transforms, and stroke. All four rows stay open: valid source decimals can lose Chromium rounding provenance, finite drawable values cross an unimplemented used-range clamp, and CSS comments plus rect auto sizes still refuse (measured, not celled); root percentage/CSS sizing and applications to unadmitted <image>/<pattern>/<mask> elements remain declared gaps. Units, CSS math, var(), and CSS-wide values retain their own unchecked rows.

SVG attributes

2026-08-24 close: the complete userSpaceOnUse | objectBoundingBox grammar is Chromium-baked, including the missing-value default, explicit user space, the exact object-box map, and invalid-value fallback. Percentages inside object-box content retain their viewport basis before that map; zero-area target boxes produce an empty clip.

2026-08-25 close: the complete case-sensitive userSpaceOnUse | objectBoundingBox grammar is Chromium-baked. Missing and invalid values take objectBoundingBox; the explicit opposite changes the filter region against a discriminating blur.

2026-08-25 close: all four arithmetic coefficients carry the complete SVG number grammar and initial zero. Individual interaction, foreground, background, and constant terms are Chromium-baked; signs, decimals, and exponents are carried, and output channels clamp to the unit interval.

2026-08-24 close: both attributes carry their complete case-sensitive userSpaceOnUse | objectBoundingBox grammar, missing-value defaults, and invalid-value fallback. Committed Chromium evidence discriminates both coordinate systems for the source image and the hard mask region, including target fill-box mapping, stroke exclusion, viewport/viewBox percentages, and explicit spellings of every enum member.

2026-08-25 close: the complete case-sensitive userSpaceOnUse | objectBoundingBox grammar is Chromium-baked. Missing and invalid values take user space; the object-box branch scales each blur axis through the target fill-geometry box.

Web checklist

On this page