VML

VML
Name	VML
Introduced	1998
Designer	Microsoft
File extension	.vml
Mime	image/vnd.microsoft.vml
Latest release version	1.1
Latest release date	1999
Genre	Vector graphics markup

VML

VML is an XML-based vector graphics markup language originally developed by Microsoft for describing two-dimensional vector and graphical elements. It was designed to enable drawing of shapes, paths, and images within document formats and web pages, and was implemented in several Microsoft products and related ecosystems. VML was standardized to a limited degree and later superseded by broader standards supported by multiple vendors.

Overview

VML provides a markup vocabulary to create primitives such as shapes, lines, curves, fills, text, and image embedding using tag-based syntax. It appeared alongside technologies like HTML 4.0, CSS, and Internet Explorer extensibility features, targeting scenarios in Microsoft Office documents, Outlook email rendering, and web pages delivered to Windows clients. The language competed and coexisted with other vector formats including SVG, PostScript, and PDF, and influenced layout tools integrated with Internet Explorer 5 and Internet Explorer 6. VML allowed programmatic manipulation through COM interfaces and scripting with JScript or VBScript in browser-hosted environments.

History

VML traces its origins to Microsoft’s efforts in the late 1990s to provide rich drawing capabilities for document and web applications, following initiatives from vendors such as Adobe Systems and work on the W3C Recommendations. It was documented in drafts submitted during discussions leading up to adoption of vector graphics technologies, and implemented inside products like Microsoft Office 2000 and Office XP. Adoption was strongest within ecosystems centered on Windows 98, Windows 2000, and later Windows XP. As Mozilla Firefox and Apple Safari grew and standards such as SVG 1.0 gained traction, cross-vendor pressure favored interoperable formats. The WHATWG and W3C communities, including stakeholders like Opera Software and Netscape Communications Corporation, advanced SVG as a more portable alternative, which gradually reduced VML’s prominence. Microsoft later shifted emphasis to supporting SVG and modern web standards with browsers like Microsoft Edge.

Technical specifications

The VML specification defines element sets for shapes, paths, text, fills, strokes, and coordinate systems. It uses XML namespaces and attributes to express geometry (for example, coordinate pairs, arc commands, and Bezier control points) and styling properties such as colors, gradients, and line styles. VML’s model includes support for layering, grouping, transforms (translate, rotate, scale), and event attributes suitable for integration with DOM scripting models used by Internet Explorer. The format supports embedding raster images (commonly JPEG, PNG, and GIF) and specifying clipping paths and viewboxes similar to features in SVG 1.1. VML files typically used the .vml extension or were inlined within HTML documents via namespaces and markup declarations understood by Microsoft’s rendering engines.

Implementations and usage

VML was implemented in Microsoft products, notably Internet Explorer (rendering engine Trident), Microsoft Office applications (Word, Excel, PowerPoint), Outlook for HTML email rendering, and server-side components in SharePoint deployments. Web developers created interactive diagrams, charts, and annotation tools using VML combined with JScript event handlers and ActiveX controls on intranet sites and enterprise portals. Third-party tools and libraries provided converters between VML and formats from Adobe Illustrator, CorelDRAW, and other desktop publishing packages. Integration scenarios included dynamic charting engines in Microsoft Exchange dashboards and document generation pipelines in BizTalk Server environments.

Compatibility and interoperability

Compatibility depended heavily on client platform and browser: VML-rendered content displayed reliably in Internet Explorer on Windows but lacked native support in browsers such as Mozilla Firefox and Google Chrome until plugin or conversion strategies were applied. Interoperability efforts involved server-side conversion to SVG or rasterization to PNG for broader delivery, and authoring tools often exported both VML and SVG to accommodate mixed-client audiences. Standards bodies like the W3C and vendor projects such as WHATWG influenced migration paths, while enterprise compatibility layers and polyfills attempted to translate VML DOM calls to SVG equivalents for cross-browser consistency.

Security and vulnerabilities

Because VML was tightly integrated with Internet Explorer and Windows scripting, security concerns centered on cross-site scripting (XSS) vectors, scriptable vector elements invoking ActiveX behaviors, and rendering bugs exploitable for code execution. Vulnerabilities were exposed in the Trident rendering engine and in document parsers used by Microsoft Office and Outlook, prompting security advisories and patches from Microsoft Security Response Center. Best practices included sanitizing VML content in untrusted documents, disabling scripting in email clients like Outlook Express, and migrating to safer, sandboxed formats supported by modern browsers such as Firefox and Chrome.

Legacy and deprecation status

VML is deprecated in modern web development and has been largely phased out in favor of SVG and canvas-based approaches standardized across W3C and implemented by browsers like Chrome, Firefox, Safari, and Edge. Microsoft announced deprecation paths in product roadmaps; later versions of Microsoft Office and Internet Explorer moved toward exporting or translating VML to SVG or raster images. Legacy enterprise documents and archived content may still contain VML markup, requiring conversion tools provided by vendors like Microsoft or third-party utilities to preserve visual fidelity during migration to contemporary formats.

Category:Vector graphics