OVF (Open Virtualization Format)
From Just Solve the File Format Problem
An OVF package consists of several files, placed in one directory. A one-file alternative is the OVA package, which is a TAR file with the OVF directory inside.
An OVF package always contains exactly one OVF descriptor (a file with extension .ovf). The OVF descriptor is an XML file which describes the packaged virtual machine; it contains the metadata for the OVF package, such as name, hardware requirements, references to the other files in the OVF package and human-readable descriptions. In addition to the OVF descriptor, the OVF package will typically contain one or more disk images, and optionally certificate files and other auxiliary files