Scalable Vector Graphics (SVG) is in most graphical tools. It is used heavily in many big projects, such as KDE (linux GUI) and Wikipedia.
The SVG specification is an open standard that has been under development by the World Wide Web Consortium (W3C) since 1999. SVG images and their behaviours are defined in XML text files which allows it to be searched, indexed, scripted and, even compressed.
Or find it on their project page.