A metafile is a file which contains information that describes or specifies another file. Microsoft use the term metafile for its Windows Metafile WMF format which is a file containing a sequences of graphical-device- interface or GDI function calls that act as commands to the Windows operating system which result in the presentation of graphic image. Some but not all of the function calls are equivalent to vector graphics statements and other literal specifications or identity stored bitmap which bits to illuminate. The reason we use WMF files rather than using an already built bitmap is because it saves disk space when many bitmaps are used repeatedly by different components of the operating system or of an application. The WMF file stays using a 16-bit operating system. Microsoft also have an enhanced metafile EMF format because it uses a 32-bit operating system, which has a much better performance rate. Another metafile that is commonly used is the Computer Graphics Metafile (CGM)which is a standard American National Standards Institute- approved format which can be used on any operating system compared to the WMF format which has been designed to only work for Windows. There are tools such as HiJaak that convert for you the WMF, EMF and CGM formats into other formats. A disadvantage of using metafiles is that it has been recorded by Symantec to Microsoft that by using a metafile to invoke a historic form of some printer management functions the Windows GDI could be tricked into executing data from the WMF file as code but this was later tackled and the vulnerability resolved using a security update in 2006. It is also possible to design alternative libraries which render WMF binary files or convert them into other graphic formats e.g. the Batik library is able to render WMF and convert them into Scalable Vector Graphics (SVG) which is the equivalent and FreeHEO Java library also allows you to save Java2D drawings as EMF files.