Inkscape Custom SVG Metadata Extensions Explained

When saving a drawing as a native “Inkscape SVG,” Inkscape embeds proprietary XML namespaces and metadata directly into the standard SVG structure to preserve editing state, parametric shapes, and GUI configurations. This article breaks down the custom namespaces Inkscape uses—primarily inkscape and sodipodi—and details the specific attributes, elements, and metadata tags injected into standard SVG code.

The Custom XML Namespaces

Standard SVG documents adhere to the W3C specification under the default XML namespace. Inkscape augments this by declaring two primary custom namespaces in the root <svg> element:

• xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape": Powers Inkscape-specific features such as layers, Live Path Effects (LPE), snapping rules, and custom transform origins.
• xmlns:sodipodi="http://www.sodipodi.sourceforge.net/DTD/sodipodi-0.dtd": Inherited from Sodipodi (the software project Inkscape was originally forked from), this namespace primarily manages canvas layout parameters and editable parametric shapes.

In addition to these, Inkscape often references standard metadata namespaces, including RDF (xmlns:rdf), Dublin Core (xmlns:dc), and Creative Commons (xmlns:cc).

Workspace and Editor State (<sodipodi:namedview>)

Inkscape stores user interface and viewport parameters within a <sodipodi:namedview> element. This block contains settings that standard SVG renderers ignore, including:

• Viewport Coordinates: inkscape:zoom, inkscape:cx, and inkscape:cy define the canvas zoom level and center coordinates from the last session.
• Window Positioning: inkscape:window-width, inkscape:window-height, inkscape:window-x, inkscape:window-y, and inkscape:window-maximized track the editor’s window geometry.
• Display Configurations: inkscape:pageopacity, inkscape:pageshadow, and bordercolor define canvas background colors and shadow effects.
• Guides and Grids: Contained elements like <inkscape:grid> and <sodipodi:guide> store user-defined alignment axes, angles, origins, and visibility settings.

Layer Management

SVG specifications do not include a dedicated <layer> element; all hierarchical grouping is handled by the standard <g> tag. Inkscape simulates layers by tagging standard group elements with custom attributes:

• inkscape:groupmode="layer": Instructs Inkscape to treat the <g> element as a distinct layer in the Layers panel rather than a standard object group.
• inkscape:label="Layer Name": Stores the human-readable name assigned to the layer or object.
• sodipodi:insensitive="true": Denotes locked layers or objects, preventing accidental user selection in the canvas.

Parametric Geometry and Node Metadata

When raw paths are drawn or primitive shapes are created, Inkscape saves the parametric variables necessary to re-edit them later using interactive handles:

• Geometric Primitives (sodipodi:type): Defines whether an object is a special shape, such as sodipodi:type="arc", sodipodi:type="star", or sodipodi:type="spiral".
• Shape Variables: Attributes like sodipodi:cx, sodipodi:cy, sodipodi:rx, sodipodi:ry, sodipodi:start, sodipodi:end, sodipodi:sides, and sodipodi:r1/r2 retain the original shape settings before converting the shape to standard d path data.
• sodipodi:nodetypes: Appears on standard <path> elements as a string of characters (e.g., sodipodi:nodetypes="ccsc"). Each character identifies the behavior of a specific path node: c (cusp/corner), s (smooth), z (symmetric), or a (auto-smooth).
• inkscape:transform-center-x and inkscape:transform-center-y: Define a custom rotational center offset for transformation operations.

Live Path Effects (LPE)

Inkscape’s Live Path Effects perform non-destructive modifications on paths. Because web browsers only render the computed geometry stored in the standard d attribute, Inkscape stores the underlying non-destructive parameters separately:

• <inkscape:path-effect>: Defined inside the <defs> section, storing parameters for modifiers such as offsets, power strokes, or fillet/chamfer operations.
• inkscape:path-effect="#effect-id": Applied directly to a path element to reference its definition in <defs>.
• inkscape:original-d: Stores the raw, unmodified path coordinates, allowing the user to modify base nodes without losing the applied Live Path Effect.

Standardized Document Metadata

Inkscape includes a <metadata> tag within the root SVG containing Dublin Core and Creative Commons schemas. This section commonly contains:

• <dc:title>: Document title.
• <dc:creator>: Author or creator information.
• <dc:date>: Creation or revision timestamps.
• <dc:rights>: Copyright conditions.
• <cc:Work> and <cc:license>: Licensing terms linked to Creative Commons URIs.

Managing Custom Metadata

These extensions ensure full non-destructive editability inside Inkscape without breaking web compatibility, as standard SVG renderers simply ignore unrecognized XML namespaces.

To create smaller, web-optimized files without proprietary tags, export the file via File > Save As and select Plain SVG or Optimized SVG, which strips all inkscape:* and sodipodi:* extensions while preserving the rendered visual output.