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SVG Element Model

Spec-grounded reference for the SVG element surface a graphical editor IR must expose. Scope: per-element geometry attributes, presentation attribute hooks, local coordinate frames, the kinds of in-place mutations that preserve byte round-trip, and cross-element constructs that resist editing. Citations link to specific sections of SVG 2, SVG 1.1, CSS Cascade 5, Filter Effects, and CSS Masking.

Conventions​

  • Presentation attributes are the painting / typography properties listed in SVG 2 §11 Painting and §13 Text: fill, fill-opacity, fill-rule, stroke, stroke-width, stroke-opacity, stroke-linecap, stroke-linejoin, stroke-miterlimit, stroke-dasharray, stroke-dashoffset, paint-order, opacity, visibility, display, color, plus text properties font-family, font-size, font-weight, font-style, text-anchor, dominant-baseline, etc. Each may be written as an XML attribute or as a CSS declaration; this doc says "presentation" to mean both encodings unless noted. See §Hazards for the cascade interaction.
  • Structural attributes mean id, class, style, transform, clip-path, mask, filter, plus ARIA / scripting hooks. They are available on essentially every rendered element; per-element sections call out only deviations.
  • Local frame describes the coordinate system the element's geometry attributes are interpreted in, before transform= is applied. Whether the element establishes a new viewport (per §7.2 Establishing a new SVG viewport) is called out explicitly.
  • Edit characterization describes what graphical mutations the editor can perform without falling back to a <path> conversion. The blanket rule: shapes have no native scale/skew attribute, so non-uniform scale, shear, and rotation must live on transform=.

rect​

Defined in SVG 2 §10.2.

  • Geometry attrs: x (init 0), y (init 0), width (init 0, must be >=0), height (init 0, >=0), rx (init auto), ry (init auto). pathLength per §10.7.
  • Presentation attrs: full fill/stroke set; see §Conventions.
  • Structural attrs: standard set.
  • Local frame: (x, y) is the top-left corner in the current user coordinate system; the rect is axis-aligned in that frame (§10.2).
  • Edit characterization:
    • translate: mutate x, y.
    • resize axis-aligned: mutate width, height (and possibly x, y for top/left drags).
    • corner radius: rx, ry.
    • rotation, shear, non-uniform scale: transform= only.
  • Round-trip hazards: rx/ry auto resolves from the other value at render time; preserve the raw token, not the resolved length. Negative width/height are an error per spec — clamp at editor boundary, do not silently rewrite.

circle​

Defined in SVG 2 §10.3.

  • Geometry attrs: cx (init 0), cy (init 0), r (init 0, >=0). pathLength permitted.
  • Presentation attrs: full fill/stroke set.
  • Structural attrs: standard.
  • Local frame: (cx, cy) is the center in the current user coordinate system.
  • Edit characterization:
    • translate: cx, cy.
    • uniform scale: r.
    • turn into an ellipse (independent x/y radii): no native path — either add transform=scale(...) (changes paint scaling, not geometry) or convert to <ellipse>. Pick one and document it; do not silently cross element type.
    • rotation: irrelevant geometrically, but transform= still mutates the rendered frame for strokes and child markers.
  • Round-trip hazards: none specific beyond shared transform vs scale ambiguity.

ellipse​

Defined in SVG 2 §10.4.

  • Geometry attrs: cx (init 0), cy (init 0), rx (init auto), ry (init auto). pathLength permitted.
  • Presentation attrs: full fill/stroke set.
  • Structural attrs: standard.
  • Local frame: (cx, cy) is the center; axes are aligned with the user coordinate system.
  • Edit characterization:
    • translate: cx, cy.
    • resize axes: rx, ry.
    • rotation: transform=rotate(...) only; ellipse has no native rotate attribute.
  • Round-trip hazards: rx/ry auto defaults to the other value per §10.4; the IR must remember which side was auto to round-trip the bytes.

line​

Defined in SVG 2 §10.5.

  • Geometry attrs: x1, y1, x2, y2 (all init 0). pathLength permitted.
  • Presentation attrs: stroke set is the meaningful subset (no fill area by default).
  • Structural attrs: standard.
  • Local frame: both endpoints in the current user coordinate system.
  • Edit characterization:
    • move endpoint A: x1, y1.
    • move endpoint B: x2, y2.
    • translate whole: mutate both endpoints; or wrap in transform=.
    • any non-translate global affine: transform= only.
  • Round-trip hazards: line accepts fill but it has no rendered effect (§10.5); do not treat author fill as dead-code and strip it.

polyline​

Defined in SVG 2 §10.6.

  • Geometry attrs: points (list of coordinate pairs, init empty). pathLength permitted.
  • Presentation attrs: full fill/stroke set. Note: polyline is not implicitly closed but the fill region is still defined by closing the polygon for fill rule purposes.
  • Structural attrs: standard.
  • Local frame: every coordinate is in the current user coordinate system (§10.6).
  • Edit characterization:
    • move vertex n: rewrite the n-th pair in points.
    • insert / delete vertex: rewrite points.
    • global affine: transform=.
  • Round-trip hazards: points permits whitespace, commas, sign packing (1-2 = 1,-2). Preserve the source token sequence; do not re-serialize on every save or you will churn diffs.

polygon​

Defined in SVG 2 §10.7.

  • Geometry attrs: points (list of coordinate pairs, init empty). pathLength permitted.
  • Presentation attrs: full fill/stroke set; the close-segment is implicit.
  • Structural attrs: standard.
  • Local frame: every coordinate is in the current user coordinate system.
  • Edit characterization: same as polyline. Adding/removing the final segment is implicit — there is no "close" toggle attribute; to un-close, switch element type to polyline.
  • Round-trip hazards: same source-token preservation hazard as polyline.

path​

Defined in SVG 2 §9; the d property is in §9.4.

  • Geometry attrs: d (init none), pathLength.
  • Presentation attrs: full fill/stroke set; fill-rule matters.
  • Structural attrs: standard.
  • Local frame: every coordinate inside d is in the current user coordinate system; commands M m L l H h V v C c S s Q q T t A a Z z per §9.3.1. Uppercase = absolute, lowercase = relative to current point.
  • Edit characterization:
    • move vertex / handle: rewrite the affected command's coordinates.
    • segment-type change (e.g. line to cubic): rewrite the command, inheriting endpoints.
    • global affine: transform= (preferred — d rewrite would lose user-authored relative/absolute structure).
  • Round-trip hazards:
    • d is a serialized mini-language. Round-tripping requires either preserving the source string verbatim when no vertex changed, or a canonical normalizer the editor commits to and the user accepts.
    • Implicit lineto after a moveto (per §9.3.3) is easy to lose in a naive parse-emit cycle.
    • pathLength is author-supplied and rescales dash arrays; do not drop it on edit.

text​

Defined in SVG 2 §11.2 Text element.

  • Geometry attrs: x, y, dx, dy, rotate (each a list, applied per-character), textLength, lengthAdjust (spacing | spacingAndGlyphs). Single-number x/y is the common case.
  • Presentation attrs: paint set plus text properties (font-family, font-size, font-weight, font-style, text-anchor, dominant-baseline, direction, writing-mode, letter-spacing, word-spacing, white-space). See §11.12.
  • Structural attrs: standard.
  • Local frame: the current text position starts at the first (x, y) from this element or inherited from ancestor. Glyphs advance along the inline-progression axis from there. (0, 0) is the anchor before the first glyph in this element's frame, not its visual top-left.
  • Edit characterization:
    • move whole block: x, y (single values).
    • per-glyph positioning: only respectable if the user authored a per-glyph list to begin with. Do not synthesize per-glyph arrays on translate of an authored single-value x.
    • rotate text block: transform=rotate(...) (the rotate= attribute is per-glyph, not block-level).
    • reflow / resize: SVG <text> does not wrap; width is implicit. Resize is not a native operation — either re-author x/y per line as separate <tspan> or accept that drag-resize is a no-op.
  • Round-trip hazards: significant whitespace handling is governed by white-space and xml:space; collapsing or re-indenting the XML silently mutates rendered content.

tspan​

Defined in SVG 2 §11.3 (shares the text-element section).

  • Geometry attrs: same set as text — x, y, dx, dy, rotate, textLength, lengthAdjust. Unspecified positions inherit the parent's current text position.
  • Presentation attrs: full text/paint set; intended primary use is overriding a property for a substring.
  • Structural attrs: standard.
  • Local frame: inherits the enclosing <text> element's coordinate system and current text position.
  • Edit characterization:
    • the canonical editor operation is "apply property X to selection [a, b)"; this is a <tspan> split. Splitting / merging tspans is not a single-attribute mutation — it restructures the XML tree.
    • geometric per-glyph positioning lives on the parent <text> or via per-character arrays here; either is legal.
  • Round-trip hazards: tspan boundaries are visible in the text node graph; splitting on every property toggle bloats the DOM, merging loses author intent. Editor must choose a normalization policy.

textPath​

Defined in SVG 2 §11.4.

  • Geometry attrs: href (the path), startOffset, side (left | right), method (align | stretch), spacing (auto | exact), textLength, lengthAdjust. Inline path= is also allowed in SVG 2.
  • Presentation attrs: text/paint set.
  • Structural attrs: standard. Note: x, y, dx, dy, rotate on a <textPath> are ignored — the path supplies them.
  • Local frame: positions are 1-D offsets along the referenced path's arclength, not 2-D coordinates. (0, 0) is not meaningful; the origin is the path start (modulated by startOffset).
  • Edit characterization:
    • slide along path: mutate startOffset.
    • flip to other side: side=left|right.
    • rebind to a different path: mutate href.
    • move-by-drag in screen space: not a native operation; the path is independent geometry. Refuse or fall back to editing the path.
  • Round-trip hazards: changes to the referenced <path> d shift the text without any local mutation; editor must invalidate.

svg​

Defined in SVG 2 §5.1. Establishes a new viewport per §7.2.

  • Geometry attrs: x, y, width, height (for inner <svg>; outermost <svg> uses CSS box on the host), viewBox, preserveAspectRatio, zoomAndPan.
  • Presentation attrs: standard paint set is accepted; primary use is overflow, color.
  • Structural attrs: standard plus xmlns, version, baseProfile.
  • Local frame: establishes a new SVG viewport and a user coordinate system. viewBox sets the user coordinates inside; preserveAspectRatio controls how that user space maps onto the viewport rectangle.
  • Edit characterization:
    • reposition inner <svg>: x, y.
    • resize: width, height; this rescales children if viewBox is set, or just enlarges the viewport otherwise.
    • rebind frame: mutate viewBox; pan = translate min-x/min-y, zoom = scale width/height.
  • Round-trip hazards: width/height as percentages vs lengths vs absent (defaults to 100%) all render the same when embedded but differ semantically; preserve the source form. CSS-property transform on <svg> applies to the outside of the element per §7.4, conceptually wrapping the element; not symmetric with transform= on inner elements.

g​

Defined in SVG 2 §5.2.

  • Geometry attrs: none. g has no x, y, width, height.
  • Presentation attrs: paint set is accepted and inherited by descendants (the primary use of g for grouped property assignment).
  • Structural attrs: standard. transform= is the only positioning knob.
  • Local frame: identity unless transform= is set. Does not establish a viewport.
  • Edit characterization:
    • translate group: transform=translate(...).
    • any other affine: transform=.
    • "set width": not a thing — group dimensions are the union of children. Drag-resize is per-child re-layout, not a group attr.
  • Round-trip hazards: ungrouping / regrouping reorders the DOM and can change cascade order if children carry presentation attrs; refuse to auto-collapse g wrappers.

symbol​

Defined in SVG 2 §5.5. Establishes a new viewport when instanced by <use>.

  • Geometry attrs: x, y, width, height, viewBox, preserveAspectRatio, refX, refY.
  • Presentation attrs: paint set is inherited by clones.
  • Structural attrs: standard.
  • Local frame: not rendered on its own. When referenced by <use>, the <symbol> establishes a nested viewport sized by the <use> geometry, with viewBox mapping the internal user space.
  • Edit characterization:
    • editing geometry attrs on <symbol> affects every <use> of it; this is reference editing, not instance editing.
    • to edit one instance, edit the <use> instead.
  • Round-trip hazards: <symbol> outside <defs> is still non-rendering by itself but participates in cascade and document order; do not collapse to <defs> membership.

defs​

Defined in SVG 2 §5.4.

  • Geometry attrs: none. Contents do not render directly.
  • Presentation attrs: accepted on <defs> but inherited by children; rarely useful.
  • Structural attrs: standard.
  • Local frame: not rendered; (0, 0) is not meaningful.
  • Edit characterization: <defs> is a non-rendering container. Edits to children (paint servers, symbols, filters) propagate to every reference. Treat as a "definition library" panel, not a canvas-editable target.
  • Round-trip hazards: some authoring tools require all referenced definitions to live inside a <defs>; others permit forward references. The spec does not require <defs> membership for referenceable elements (§5.4).

switch​

Defined in SVG 1.1 §5.8 (SVG 2 carries the element with the same behavior).

  • Geometry attrs: none.
  • Presentation attrs: standard set; transform= allowed.
  • Structural attrs: standard. Children are evaluated against systemLanguage, requiredExtensions, requiredFeatures (last is SVG 1.1 only — SVG 2 deprecates it).
  • Local frame: identity; rendering frame of whichever child is selected.
  • Edit characterization: the rendered child is the first child whose conditional attrs all evaluate true. A graphical editor cannot meaningfully select the "child" without first picking a locale context. Editing siblings is editing the unrendered branches.
  • Round-trip hazards: see §Hazards.

use​

Defined in SVG 2 §5.6.

  • Geometry attrs: x, y, width, height, href (or legacy xlink:href).
  • Presentation attrs: paint set is inherited by the cloned subtree unless overridden in the source.
  • Structural attrs: standard.
  • Local frame: the cloned content is rendered as if it were a shadow tree at the <use> element's position. width/height only have effect when the referent is <svg> or <symbol> (overriding their viewport sizing).
  • Edit characterization:
    • move instance: x, y.
    • resize: only meaningful for symbol/svg referents.
    • global affine: transform=.
    • edit instance contents: not possible directly — the shadow tree is read-only per §5.6.1: "Any attempt to directly modify the elements, attributes, and other nodes in the shadow tree must throw a NoModificationAllowedError." Editing the referent is the only path; it changes every instance.
  • Round-trip hazards: circular <use> references are invalid and must not render. Editor must reject creation of cycles.

linearGradient​

Defined in SVG 2 §13.2.

  • Geometry attrs: x1 (init 0%), y1 (init 0%), x2 (init 100%), y2 (init 0%), gradientUnits (init objectBoundingBox), gradientTransform, spreadMethod (pad | reflect | repeat), href (template).
  • Presentation attrs: not a render target; child <stop> carries stop-color, stop-opacity.
  • Structural attrs: standard.
  • Local frame: depends on gradientUnits:
    • userSpaceOnUse — coordinates in the user coordinate system at the referencing element's position.
    • objectBoundingBox (default) — 0..1 maps to the referencing element's bounding box.
  • Edit characterization: not an edit target on the canvas; edits happen via paint pickers operating on the referencing element's fill/stroke. The IR must surface gradient handles in the picker's frame, not the document's.
  • Round-trip hazards: objectBoundingBox coordinates are unit square; the editor cannot present them in document pixels without knowing the current referent. href chains let one gradient inherit stops or geometry from another — partial overrides.

radialGradient​

Defined in SVG 2 §13.3.

  • Geometry attrs: cx (init 50%), cy (init 50%), r (init 50%), fx, fy (init equal to cx, cy), fr (init 0%), gradientUnits, gradientTransform, spreadMethod, href.
  • Presentation attrs: see linear gradient.
  • Structural attrs: standard.
  • Local frame: same userSpaceOnUse / objectBoundingBox split as linear.
  • Edit characterization: as linear; the focal-point handles (fx, fy, fr) are extra UI affordances.
  • Round-trip hazards: fx/fy default to cx/cy — preserve absence vs equal-value to round-trip.

pattern​

Defined in SVG 2 §13.4.

  • Geometry attrs: x, y, width, height, patternUnits (init objectBoundingBox), patternContentUnits (init userSpaceOnUse), patternTransform, viewBox, preserveAspectRatio, href.
  • Presentation attrs: not a render target.
  • Structural attrs: standard.
  • Local frame: tile rectangle established by patternUnits; tile content uses patternContentUnits — note the two axes can be different units, which is a common authoring footgun.
  • Edit characterization: paint server; same as gradients — not a canvas-direct target.
  • Round-trip hazards: patternUnits and patternContentUnits defaults differ; canonical normalization will change rendering for documents that relied on defaults.

marker​

Defined in SVG 2 §11.6 Marker properties.

  • Geometry attrs: refX, refY (length, percentage, or keyword: left/center/right for refX; top/center/bottom for refY), markerWidth, markerHeight, markerUnits (strokeWidth | userSpaceOnUse), orient (auto | auto-start-reverse | angle), viewBox, preserveAspectRatio.
  • Presentation attrs: inherited by marker contents.
  • Structural attrs: standard.
  • Local frame: a viewport sized by markerWidth × markerHeight; viewBox sets the user-space mapping; refX/refY is the point inside that frame that aligns to the vertex being decorated.
  • Edit characterization: glyph decorator; edited via the picker attached to marker-start / marker-mid / marker-end on the referent. Per-instance rotation comes from orient=auto, not from the marker element itself.
  • Round-trip hazards: markerUnits=strokeWidth (default) means marker size depends on the referent's stroke-width; resizing a marker by mutating markerWidth rescales every reference.

clipPath​

Defined in CSS Masking Module §6; historical attributes per SVG 1.1 §14.3.5.

  • Geometry attrs: clipPathUnits (userSpaceOnUse (default) | objectBoundingBox). The clipping geometry lives in child shape elements.
  • Presentation attrs: clip-rule on children matters; paint is ignored.
  • Structural attrs: standard.
  • Local frame: per clipPathUnits. With userSpaceOnUse, child shapes are in the user coordinate system at the referencing element; with objectBoundingBox, they are in unit-square coordinates of the referent's bbox.
  • Edit characterization: clip-shape editing is editing the child shape's native attributes; not a <clipPath>-attribute mutation.
  • Round-trip hazards: CSS clip-path property and SVG <clipPath>
    • clip-path=url(#...) attribute are different surfaces with different syntax (inset(), polygon(), etc. for CSS); preserve the original form.

mask​

Defined in CSS Masking Module §8; historical attributes per SVG 1.1 §14.4.

  • Geometry attrs: x (init -10%), y (init -10%), width (init 120%), height (init 120%), maskUnits (init objectBoundingBox), maskContentUnits (init userSpaceOnUse), mask-type (luminance (default in SVG 1.1) | alpha).
  • Presentation attrs: mask region paint is honored; color and filters apply.
  • Structural attrs: standard.
  • Local frame: split — region rectangle in maskUnits, content in maskContentUnits. Defaults differ (region = bbox unit square, content = user space); a common rendering surprise.
  • Edit characterization: paint a mask = edit the child rendering tree; reposition the mask region = mutate x/y/width/height.
  • Round-trip hazards: same dual-units surprise as <pattern>.

filter​

Defined in Filter Effects Module §6; historical attributes per SVG 1.1 §15.5.

  • Geometry attrs: x (init -10%), y (init -10%), width (init 120%), height (init 120%), filterUnits (init objectBoundingBox), primitiveUnits (init userSpaceOnUse), href (template); filterRes is SVG 1.1 only and deprecated.
  • Presentation attrs: irrelevant to the filter element itself; primitives carry their own.
  • Structural attrs: standard.
  • Local frame: filter region in filterUnits; primitive lengths in primitiveUnits. Same dual-units pattern as mask and pattern.
  • Edit characterization: filter editing means editing the primitive children (<feGaussianBlur>, <feColorMatrix>, …), which is a node-graph editor, not a single-attribute mutation.
  • Round-trip hazards: filter primitive graphs have implicit in/result chaining; deleting a primitive can break downstream references silently. CSS filter property and SVG <filter> + filter=url(#...) are separate surfaces.

image​

Defined in SVG 2 §9 Embedded content.

  • Geometry attrs: x, y, width, height, href, preserveAspectRatio, crossorigin.
  • Presentation attrs: image-rendering, opacity, visibility, clip-path, mask, filter apply; fill/stroke do not paint the bitmap.
  • Structural attrs: standard.
  • Local frame: (x, y) is the top-left of the positioning rectangle in user coordinates; the bitmap is fitted into that rectangle by preserveAspectRatio. overflow:hidden by default per spec — content that violates aspect ratio fit is clipped.
  • Edit characterization:
    • move: x, y.
    • resize: width, height.
    • rebind asset: href.
    • crop: not native — wrap in <clipPath> or use a CSS aspect-ratio override.
  • Round-trip hazards: data-URI href payloads are large and whitespace-sensitive; the IR must hold the raw href token, not a decoded blob.

style​

Defined in SVG 2 §6.4.

  • Geometry attrs: none.
  • Presentation attrs: none (style is a sheet, not a graphic).
  • Structural attrs: type (init text/css), media (init all), title.
  • Local frame: not rendered.
  • Edit characterization: a CSS text node. Mutating a single selector's value can affect any number of canvas elements that match it. Not a direct graphical mutation target; either treat as opaque source or refuse edits that round-trip through inline-style conversions. See §Hazards.
  • Round-trip hazards: the cascade.

foreignObject​

Defined in SVG 2 §9.8.

  • Geometry attrs: x, y, width, height. No preserveAspectRatio and no href.
  • Presentation attrs: overflow, opacity, visibility, plus applicable CSS layout on contents.
  • Structural attrs: standard.
  • Local frame: the rectangle is a CSS containing block for the foreign-namespace contents; child layout follows the foreign language's model (HTML/CSS for xmlns="http://www.w3.org/1999/xhtml", MathML, etc.).
  • Edit characterization: only the SVG-side rectangle is editable in the canvas. The contents are an embedded foreign document — out of scope for a vector editor; treat as opaque.
  • Round-trip hazards: see §Hazards.

Hazards (cross-cutting)​

Constructs that resist round-trip graphical editing across element types.

  • <style> cascade. Per SVG 2 §6.3 Presentation attributes: "Presentation attributes contribute to the author level of the cascade, following all other author-level style sheets, and have specificity 0." Mutating an inline fill= attribute on a rect is a no-op if a <style> selector with specificity ≥ 1 targets that rect. The IR must read computed style, not the attribute alone, before reporting a property's effective value; writes that "set fill to red" must either edit the matching CSS rule or wrap in an inline style="fill:red" (specificity 1,0,0,0) that overrides — neither preserves source structure.
  • SMIL <animate>, <animateTransform>, <set>, <animateMotion>. Per SVG 2 §19 (SVG 2 retains SMIL by reference). A property's rendered value at any instant may differ from its base value. Edit decisions must use the base value; visual feedback must reflect the animated value or be honest about the divergence.
  • <switch> language branching. Per SVG 1.1 §5.8: "The switch renders the first of its children for which all of these attributes test true." The visually selected child depends on the user agent locale; editing "the rendered text" silently mutates only one locale's branch.
  • <foreignObject> content. A foreign-namespace document tree (HTML, MathML) inside an SVG. The vector editor's primitives do not apply.
  • Foreign-namespace metadata. sodipodi:*, inkscape:*, xmlns:adobe-illustrator, xmlns:graph and similar are non-SVG attributes the editor must preserve verbatim or it will silently break the source tool's edit semantics. The SVG namespace rules (SVG 2 §1.4) permit any foreign namespace; preserve, do not normalize.
  • CSS transform property vs transform= attribute. Per SVG 2 §7.4: the CSS transform property "applies conceptually to the outside of the svg element" — it composes differently from the transform= attribute. Two visually identical documents can encode transforms in either surface; round-trip requires preserving the original.
  • Presentation attribute vs inline style cascade. Same property may appear as fill="red" and as style="fill:blue" on the same element; the inline style wins (specificity 1,0,0,0 vs 0 for the presentation attribute, per §6.3). Reading must consult both; writing must decide which surface to mutate and remember.
  • Percentage units. width="50%" on an <svg> resolves against the host viewport; on a <rect> it resolves against the nearest viewport's viewBox width/height per §7.11 Units. Resize via drag computes a pixel delta — converting that to a percentage requires the viewport context and a policy choice (preserve unit type vs always store user units).
  • viewBox vs width/height. With both set, drag-resize at the document edge can mean "rescale content" (mutate width/height, hold viewBox) or "extend canvas" (mutate viewBox, hold width/height). Both are spec-valid per §7.5 viewBox; the editor must commit to a model and surface it.
  • <use> shadow tree. Per SVG 2 §5.6.1: the shadow tree is read-only; "Any attempt to directly modify the elements, attributes, and other nodes in the shadow tree must throw a NoModificationAllowedError." Per-instance edits are fundamentally not supported on a <use> clone.
  • Path d source fidelity. The d mini-language (SVG 2 §9.3.1) admits many equivalent encodings (relative vs absolute, implicit lineto, whitespace, sign packing). Any parse-emit cycle that does not preserve untouched substrings churns the source.