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 and feDiffuseLighting attribute routes now carry admitted subsets, but neither creates a CSS computed-value route or changes 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.

<defs>
<desc>
<ellipse>
<feBlend>

2026-08-26 close: feBlend carries the complete static sixteen-mode Compositing Level 1 vocabulary over two checked image inputs. Chromium-baked evidence covers opaque and translucent arithmetic, foreground/backdrop order, graph fallbacks and result reuse, both filter color spaces, hard regions and primitive units, source shapes and paint servers, <use>, viewBox, safe mappings, opacity and mask order, and neighboring admitted filter operations. General target mappings, geometric clipping, and the independently discovered translucent-source multi-input composition class refuse by three stable precision names before paint. Shared graph, region, interpolation, filter-resource, and dynamics rows remain open. Hosted x86 initially contradicted the ARM-local blend result in eight cells. The pinned backend's low-precision path divides by 255 exactly on NEON but approximates that step as division by 256 on x86. Nine modes now state their exact byte-domain arithmetic; the seven high-precision modes remain native. That repair removed seven failures and every opaque mismatch. One translucent atlas remained at 2,816 pixels / delta 1 across eleven mode tiles, locating a separate final sRGB layer-restore split. A blend-scoped exact restore closes it and clears across later color-space conversion. The complete 572-cell gate is exact on ARM and hosted x86 with no tolerance. Restoring the approximate division made twelve blend cells fail locally, up to 4,096 pixels / delta 3; restoring exact arithmetic returned the gate to green.

<feColorMatrix>
<feComponentTransfer>
<feComposite>
<feConvolveMatrix>

2026-08-27 close/split: feConvolveMatrix carries Chromium's complete static convolution behavior: rectangular kernels through 256 coefficients, kernel reversal, divisor and bias arithmetic, asymmetric targets, all three edge modes, alpha preservation, both filter color spaces, graph inputs and reuse, hard regions and primitive units, safe mappings, source geometry, blur/morphology ordering, target effects, <use>, and viewBox. Invalid operation states and Chromium's 257-coefficient construction limit produce the browser's transparent result rather than an unfiltered fallback. Chromium ignores kernelUnitLength on this primitive; the drop is celled, while that attribute row stays open for its lighting applicability. General affine mappings, paint-server source images, and a divisor whose reciprocal exceeds finite resolved arithmetic refuse by three stable names before paint. Forty exact convolution cells and one blur-edge drop cell move the complete gate to 741. Removing the required kernel reversal makes eleven cells fail, up to 2,814 pixels and maximum channel delta 250; restoration returns the gate to green. The shared graph, region, interpolation, filter-resource, and dynamics rows remain open.

2026-08-25 close: component transfer carries the complete static direct-child vocabulary for all four channels: missing channels are identity, later same-channel children win, and identity | table | discrete | linear | gamma resolve through exact byte lookup tables. The committed Chromium evidence covers straight RGBA, alpha creation/removal, both filter color spaces, graph inputs, regions and units, safe transforms, shapes, stroke, <use>, and neighboring filter operations. Paint-server sources and the unsafe transform envelope remain named backend-precision refusals; the generic same-scope clip-plus-opacity boundary is likewise quarantined before paint. Transfer-function animation remains a separate open axis.

2026-08-26 close: feMorphology carries the complete static case-sensitive erode | dilate operation and SVG <number-optional-number> radius grammar. Missing and invalid operation text selects erode; missing and invalid radius text selects zero; one number supplies both axes; and negative members clamp independently to zero, so the other axis remains active. Chromium-baked evidence covers mapped half-step rounding, non-uniform viewBox and object-box units, SourceAlpha and generated inputs, result reuse, hard regions, both filter color spaces, premultiplied channel extrema, paths, strokes, rounded rectangles, <use>, safe mappings, target effects, and ordering with the admitted filter family. General affine mappings, paint-server source images, and active filled-circle/ellipse sources refuse by three stable precision names before paint; the last boundary leaves the older fill-only ellipse issue to gridaco/nothing#88. Thirty-seven exact cells move the complete gate to 609 cells, and swapping erosion with dilation makes thirty-five of those cells fail loudly. The shared operator, radius, graph, region, color, filter-resource, and dynamics rows remain open for their wider applicability. The first full-workspace hosted-x86 run contradicted the ARM-local result in nine active sRGB morphology cells: 1,633 pixels differed in total, all by one channel level. They shared the final filter-layer restore, where the pinned backend's low-precision division differs by CPU family. An active-sRGB-scoped exact byte-domain restore clears the class; zero radius and later color-space conversion retain their prior paths. The complete 609-cell gate is exact on ARM and hosted x86 without tolerance.

<feOffset>
<fePointLight>
<feSpecularLighting>
<feSpotLight>

2026-08-27 close/split: feDiffuseLighting reads one input alpha field and closes with all three direct light kinds. The first recognized direct light child wins; non-light children are skipped, nested lights do not participate, and no light produces transparent black. Exact cells cover distant, point, and spot illumination; opaque output alpha; signed surface height; object-box x/y/normalized-diagonal-z mapping; both filter color spaces; graph inputs; hard regions; <use>, viewBox, stroke and gradient alpha; target effects; safe transforms; and neighboring filter operations. General affine mappings and one narrow feComposite foreground placement refuse by stable precision names. Seventy-one exact cells move the complete gate to 812. Halving the diffuse coefficient makes sixty-one of them fail, up to all 4,096 pixels and maximum channel delta 128; restoration returns the gate to green. feSpecularLighting remains open behind the advanced transactional primitive witness.

<feTile>
<feTurbulence>

2026-08-26 close: feTurbulence carries both static procedural-noise formulas, the complete five-parameter attribute vocabulary, generated-source regions, both filter color spaces, graph reuse, safe mappings, <use>, and viewBox. feDisplacementMap carries two ordered images, signed scale, all four non-premultiplied channel selectors, hard regions and object-box units, color conversion, source/generated/procedural maps, source shapes, opacity, safe mappings, <use>, and viewBox. A user-space procedural filter may paint even when its target contributes a fully transparent source; an object-box filter region on the same zero-area target paints nothing. Ninety-one exact Chromium cells move the complete gate to 700. General affine mappings for both primitives and geometric clipping for displacement refuse by three stable precision names before paint. The shared type, in, in2, result, region, interpolation, filter-resource, and dynamics rows remain open for their wider applicability. Swapping the two noise formulas and red/alpha displacement selection made fifty-five new cells fail, up to all 4,096 pixels and maximum channel delta 202; restoration returned the complete gate to green. A review-triggered color-space/operation matrix found that procedural images must remain floating through blend arithmetic, while active sRGB morphology materializes a direct procedural image. Restoring the old policy makes five dedicated cells fail at up to 2,365 pixels and maximum channel delta 6. The first hosted-x86 run found 294 one-code-value pixels across twenty-two displacement/procedural cells. Its first repair cleared all eighteen displacement failures; the second hosted run left 729 delta-1 pixels across four procedural cells, including 726 in the blend control. Pinned Skia source and a four-atlas, sixty-four-mode Chromium replay then separated direct sRGB byte-domain blend products from promoted floating products and made every atlas exact. Six committed difference/exclusion controls guard both routes: forcing floating arithmetic breaks the two direct controls by 3,497 and 3,532 pixels, while forcing byte arithmetic breaks the four promoted controls by 3,287–3,697 pixels. A further thirty-four-source operation-chain matrix found that an sRGB blend result materializes before a later blend; carrying the earlier floating state silently changed 3,468 and 3,700 pixels. Two committed chain controls now guard that transition. Explicit procedural mode arithmetic and composed-result half-up quantization kept all 700 ARM cells exact. The third hosted-x86 run cleared the 726-pixel blend control and left three singleton delta-1 pixels: one each in the default-color, linear-color, and stitched procedural controls. Pinned Skia source located that final split in process startup: no caller initialized the runtime-selected raster pipeline, so hosted x86 retained baseline non-fused Perlin arithmetic while ARM used its fused NEON path. Initializing Skia before drawlist replay selects x86 AVX2's fused path as well. The fourth hosted-x86 gate and the ARM gate are byte-exact across all 700 cells, with no tolerance.

<filter>

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. The later convolution rung commits that drop and closes the shared attribute row; it does not close the blur element's other remainders. 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.

<metadata>
<mpath>
<path>
<pattern>

2026-08-27 split: same-document patterns now resolve per consuming fill or stroke into a bounded, source-neutral repeating vector program. Both unit systems, independent clients, template chains, viewBox mapping, cascade, transforms, <use>, effects around the target, nested repetition, and the invalid-reference-fallback versus valid-empty distinction are carried by 62 exact Chromium cells. The element stays open: external template facts, unsupported source descendants, curved source coverage, isolated source effects, mixed nested composition, used-length saturation, fractional tile sampling, and general affine mapping refuse by stable name at measured pixel boundaries. A ninth distinct nested program now refuses before source compilation begins. Shared x/y/width/height, href, viewBox, CSS-token/value-type, resource, and dynamics rows remain independently open.

2026-08-27 composition split: 62 further exact Chromium cells admit a pattern selected through all four fill/stroke × context-fill/context-stroke crossings, filters inside the resolved tile program, and pattern paint as a filter source in the measured direct sharp-rectangle profile. The element remains open. A source-derived filter over curved, rounded, multi-draw, or otherwise wider pattern-painted target geometry now refuses at its own measured filtered-pattern coverage boundary; every P1 source-coverage/effect/nesting boundary above also remains. External I/O, unsupported source descendants, and pattern dynamics are unchanged. No checklist row closes in this composition rung.

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.

2026-08-27 split: direct lighting-color on admitted diffuse lighting carries initial white, the admitted sRGB color subset, currentColor, reset and invalid fallback, non-inheritance, and Chromium's rule that light-color alpha is ignored. Missing filter interpolation is linearRGB and explicit sRGB remains distinct. Explicit inheritance, CSS ingress, var(), and wider color functions refuse by four stable names under their independently listed rows. The presentation-attribute row also applies to the still-open specular primitive, so it does not tick; its CSS property twin is absent at the pinned cascade and stays separately open.

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

2026-08-26 close: baseFrequency applies only to feTurbulence and carries the complete SVG one-or-two-number grammar. One value supplies both axes; comma-wsp, leading plus, exponent, and the measured lone trailing comma are carried. Missing, malformed, unit-bearing, and overlong lists select the initial zero pair; either negative member makes the whole pair initial.

bias

2026-08-27 close: convolution bias carries one signed SVG number with initial zero; missing, empty, malformed, unit-bearing, CSS-function, and CSS-wide text selects that initial. divisor carries the same one-number grammar. Missing, exactly empty, and explicit positive or negative zero use the kernel's ordered binary32 sum; a zero sum becomes one. A present nonempty malformed divisor uses one. Signed nonzero divisors remain active. The wider invalid-spelling matrix is measured, not all separately celled.

class
clipPathUnits

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.

2026-08-27 close: the complete case-sensitive duplicate | wrap | none grammar is Chromium-baked at actual input boundaries; missing and every invalid spelling select duplicate. The attribute's other listed applicability is blur, where current Chromium drops all spellings; one committed drop cell records that browser behavior.

elevation
exponent
fetchpriority
filterUnits

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.

kernelMatrix
kernelUnitLength

2026-08-27 close/split: kernelMatrix carries the complete SVG number-list grammar and must contain exactly order-x × order-y values. Missing, malformed, non-finite, or wrong-count matrices produce the measured transparent result. Kernels at the measured native strategy boundaries—28, 29, 64, 65, and 256 coefficients—are exact; 257 coefficients produce the celled Chromium drop. Current Chromium also ignores every sampled valid and invalid spelling on diffuse lighting, with valid and invalid drop cells, and sampled specular controls reproduce that result. kernelUnitLength stays open until the specular primitive itself is admitted.

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.

media
method
mode

2026-08-26 close: mode applies only to feBlend and carries the complete case-sensitive normal | multiply | screen | overlay | darken | lighten | color-dodge | color-burn | hard-light | soft-light | difference | exclusion | hue | saturation | color | luminosity grammar. Missing, empty, invalid, wrong-case, whitespace-padded, legacy camelCase, CSS-wide, and draft-only spellings select the initial normal; Chromium ignores the sampled no-composite spelling without changing a valid mode.

numOctaves

2026-08-26 close: numOctaves applies only to feTurbulence. Missing or invalid integer text selects one, leading plus and surrounding SVG whitespace are carried, positive values cap at nine, zero reaches the selected formula, and a negative integer produces the measured transparent result.

2026-08-27 close: convolution order carries one or two values; one supplies both axes, and Chromium truncates each finite value toward zero. Missing, empty, malformed, wrong-count, unit-bearing, CSS-function, and CSS-wide text selects the initial 3×3 order. A parsed non-positive member or an unconstructable finite area produces the measured transparent result. The wider invalid-spelling matrix is measured, not all separately celled.

2026-08-27 close/split: the complete case-sensitive userSpaceOnUse | objectBoundingBox grammars, their different initials (userSpaceOnUse for content, objectBoundingBox for the tile), and invalid fallback are Chromium-baked, so patternContentUnits and patternUnits close. patternTransform stays open: translation, axis scale, reflection, and exact quarter turns are admitted through the transform presentation hint, but valid general rotations and shears cross the measured picture-shader precision boundary; one derived-template stylesheet transform:none provenance case also refuses by name. The shared CSS transform route remains separate and open: Chromium resolves an inline percentage translation on <pattern> against the root viewport, while the former tile-width basis changed 1,008 pixels at maximum delta 205. That computed percentage now refuses until its reference box is proved rather than invented (measured, not celled).

2026-08-27 close: the complete case-sensitive false | true grammar is Chromium-baked. Missing and invalid spellings select false; committed SourceAlpha and positive-bias pairs distinguish convolved alpha from preserved input alpha.

preserveAspectRatio
primitiveUnits

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.

2026-08-26 close: displacement scale and turbulence seed each carry the complete signed SVG-number grammar with initial zero, including leading plus, exponent, and the measured lone trailing comma. Invalid, unit-bearing, percentage, CSS-function, and multi-member text selects the initial. Scale keeps its sign and fractions; the noise formula truncates fractional seed values toward zero as Chromium does.

2026-08-26 close: stitchTiles applies only to feTurbulence and carries the complete case-sensitive stitch | noStitch grammar. Missing, empty, invalid, wrong-case, whitespace-padded, and CSS-wide spellings select the initial noStitch; stitched fractional primitive regions are Chromium-baked.

style
surfaceScale

2026-08-27 close/split: the eight diffuse/light-only attributes tick at their complete signed SVG-number behavior. surfaceScale and diffuseConstant have initial one; an exactly empty attribute becomes zero, while whitespace-only or malformed text takes the initial. Surface height keeps its sign and a negative diffuse constant clamps to zero. Azimuth and elevation are signed and periodic. Spot targets default independently to zero. limitingConeAngle uses the measured 90-degree behavior when missing, zero, or outside ±90; a negative in-range angle equals its positive magnitude. Leading plus, exponent, trailing-comma prefix, finite extremes, underflow, and overflow fallback were measured across the family. The wider invalid-spelling matrix is measured, not all separately celled. Shared x/y/z remain open for their other element applicability, and specularExponent remains open for feSpecularLighting even though the spot light's initial one and inclusive 1–128 clamp are carried.

systemLanguage
tabindex
tableValues

2026-08-25 close: the five function-parameter attributes close at their complete applicability to <feFuncR>/G/B/A. amplitude and exponent carry gamma's initial one; offset remains open because it is a wider shared attribute. slope carries linear's initial one, intercept its initial zero, and tableValues carries the complete SVG number-list grammar for table/discrete, including absent, empty, singleton, multiple, malformed, signed, exponent, separator, trailing-comma, and out-of-range cases. Blink's ordered source-number normalization, function arithmetic, clamping, and byte truncation are Chromium-gated. The wider shared type row remains open.

target
targetX
targetY

2026-08-27 close: both target coordinates carry the signed SVG-integer grammar. Missing values default independently to the floor of half their order axis. An authored lexical failure or integer-storage overflow selects zero; a valid negative or value outside its kernel axis produces the measured transparent result. Asymmetric x/y cells distinguish both coordinates.

2026-08-26 close: both displacement selectors carry the complete case-sensitive R | G | B | A grammar independently. Missing, empty, invalid, wrong-case, whitespace-padded, and CSS-wide spellings select the initial A; committed pairs prove that selection occurs on the non-premultiplied displacement image.

Web checklist

On this page