A Virtual CD Image is an ISO-formatted directory database that indicates how files will be arranged on your CD. The image contains pointers to where those to-be-recorded files actually reside on your drives, while the actual contents of the files or directories are still on the original storage media.
It also refers to a database of files to be written to CD with Easy-CD Pro for Windows 3.1, created by dragging & dropping files into the main window. It can be used to write directly to CD on-the-fly or to record a real ISO 9660 image to hard disk.