UDF is the abbreviation of Universal Disc Format; it is compatible with the ISO 9660 format. It uses a standard technology package to write; users can modify and delete files on a CD-ROM.
While burning with UDF format, the CD burning software will packet the data and establish a special but temporary file directory table in the memory, at the same time, it will take over the access to CD. Deleted files or modified files are still in CD-R partially. The revised part of data will be written in CD separately. In the directory table in memory, data can be restructured by setting permission to access special links. All this can make the system have no access to old data, and the new data will take the place of old data. So the old data shall be deleted. After the operation of users, this will help them to rewrite the new directory into CD and record the operation content. The above process will make it convenient for the read in and data recovery of CD.
While using UDF, users can burn CD through a drag operation like operations on hard disk under Windows Explorer.
At present, all software with UDF can support the burning of CE-RW. But there are some subtle differences. The deleted files are really deleted, and it is not the way like above said. The only shortcoming of UDF is that it reduces the valid storage space, moreover, a format to CD-R/CD-RW is required, but the format will reduce the CD-RW by 100 MB or so. In the lower version of Windows Systems, the read of CD-RW disc with UDF format needs the support of software.