Partial disc image file created by VirtualDrive, a disc imaging and burning application; saves one part of an overall disc image where other parts use the extensions ".d01," ".d02," etc.; used when the size limit of a disc image is exceeded so that the volume is split across multiple files. D00 files save data in a format that can be burned to a disc or mounted as a virtual disc in the software when used with the other disc parts. These files are used for backups and for mounting disc data without having to insert the physical disc. NOTE: VirtualDrive uses the .VCD extension for full disc images. When disc images are split into multiple files, the files may use the compound extensions ".vcd.d00," ".vcd.d01," etc.