Vector Markup Language is an obsolete XML-based file format for two-dimensional vector graphics. It was specified in Part 4 of the Office Open XML standards ISO/IEC 29500 and ECMA-376. According to the specification, VML is a deprecated format included in Office Open XML for legacy reasons only. VML was used extensively in MS Office 2007 Word, Excel and PowerPoint documents. In 2012, with the release of Internet Explorer 10, VML became obsolete and is no longer supported by Internet Explorer standard mode. It is a legacy feature that is available in Internet Explorer 10 only when the browser is set to run in modes that emulate the functionality of previous versions of Internet Explorer 6, 7, 8, and 9.
Below is a VML instance as produced by Microsoft Excel 2010: xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:x="urn:schemas-microsoft-com:office:excel"> path="m,l,21600r21600,l21600,xe">
4, 15, 5, 10, 6, 31, 9, 9 False 6 3
Note that, by specifying a root element named "xml", VML contravenes the XML Recommendation of the W3C, which states that names beginning 'x' 'm' 'l' are "reserved for standardization in this or future versions of this specification". VML, when embedded within HTML markup, is read and processed by Microsoft Internet Explorer ; for example, the following example displays a solid blue oval:
Implementations
VML is used by most Microsoft Office applications, such as Microsoft Word and Microsoft Visio, within HTML files created using the 'Save As HTML' option. Such files retain complete vector information, and can be reopened for editing using other Microsoft applications, such as Microsoft PowerPoint. VML was natively supported by Microsoft's Internet Explorer up to version 9 inline within HTML, using an undefined version of SGML namespaces. Support for VML was dropped in Internet Explorer 10 and subsequent versions. Support for "ink annotations" in Office Open XML files was added to LibreOffice during the 3.7 development cycle. VML is not natively supported by most web browsers. Web browsers such as Mozilla Firefox, Opera, Safari or Google Chrome support Scalable Vector Graphics instead of VML.
Though VML is deprecated as a standard in Internet Explorer, it is most commonly used in relation to the development of HTML emails rendered in Microsoft Outlook 2007, 2010, and 2013. The use of background-images in email campaigns requires the use of VML to be displayed in Outlook because Outlook does not support the CSS or HTML attributes for background-images.