L.5.1 Introduction

This subclause provides an overview of the most common parts of VML. The VML format is a legacy format originally introduced with Office 2000 and is included and fully defined in ISO/IEC 29500 for backwards compatibility reasons. The DrawingML format is a newer and richer format created with the goal of eventually replacing any uses of VML in the Office Open XML formats. VML is a transitionalformat; it is included in Office Open XML for legacy reasons only .

Conversion from VML to DrawingML can result in information loss, as they use different models. For example,

VML uses a flat XML structure, whereas DrawingML uses one that is hierarchical. In general, inferring hierarchical structure from flat XML is much more difficult than generating flat XML from a hierarchy. VML allows combinations of attributes that are mutually incompatible in DrawingML.

VML is an XML-based exchange, editing, and delivery format for high-quality vector graphics. VML facilitates the exchange and subsequent editing of vector graphics between a wide variety of productivity and design applications. VML is based on XML 1.0, which is an open, simple, text-based language for describing structured data. VML also supports other World Wide Web Consortium standards, such as Cascading Style Sheets 2.0 (CSS), which specifies style information and 2-D positioning.

As the VML format is a format provided for backward compatibility, many VML elements are defined in the same urn:schemas-microsoft-com:vml namespace that is currently used by millions of documents already using VML. In the documentation this is typically shortened to a v: prefix in the VML tag by defining xmlns:v=“urn:schemas-microsoft-com:vml”. The namespaces used for VML are

legacy namespaces. Once again, VML should be considered a deprecated format included in Office Open XML for legacy reasons only and new applications that need a file format for drawings are strongly encouraged to use preferentially DrawingML .

Additional elements and attributes are defined in namespaces that reflect how they are used (all VML namespaces defined in ISO/IEC 29500 maintain the legacy namespace structure for backward compatibility):