F.1.2 DICOM file ID mapping

The ISO 9660 standard provides a hierarchical structure for directories and files within directories. Each volume has a root directory that may contain references to both files and subdirectories. Subdirectories may contain reference to both files and other subdirectories.

F.1.2.1 FILE ID

A volume may have at most 8 levels of directories, where the root directory is defined as level 1. The nomenclature for referring to a file in the ISO 9660 standard is dependent upon the receiving system. For the purposes of this document, the following notation will be used:

a) / – For the root directory

b) /FILENAME.;1 – For a file in the root directory

c) /SUBDIR – For a subdirectory in the root directory

d) /SUBDIR/FILENAME.;1 – For a file in the subdirectory

Given a File ID consisting of N components, referred to as Comp1 through CompN, then the corresponding ISO 9660 file shall be named /Comp1/.../CompN.;1

The ISO 9660 File Name Extension shall not be used.

The ISO 9660 standard requires the two separators "." and ";" to demarcate a "File Name Extension" and a "Version Number". To remain compatible with the ISO standard, the version number shall be 1.

Notes: 1. The above specified file ID mapping corresponds to ISO 9660 Level 1 compliance. This ensures the greatest level of compatibility across receiving systems.

2. The following is an example of the DICOM to ISO 9660 file mapping:

DICOM File ID ISO 9660 File Name

3. The ISO 9660 File Name written on the media as described above is not necessarily the name that an application will use in interacting with an operating system or CD-R writing utility. For example, the application will generally create a directory structure, and the OS or utility will create the correct full path file names with “/” characters. Similarly, the application generally will not need to append the dot character and “;1” version identifier to the name, as these will be added by the OS or utility to create an ISO 9660 compliant File Name. In fact, if the application appends “;1” to the name, and the OS or utility supports the Rock Ridge or Joliet extensions, those characters may be interpreted as part of the application specified file name rather than the file version identifier; a further file version identifier may be appended, resulting in an incorrect file name such as “/DICOMDIR.;1.;1”.


A DICOMDIR file in a DICOM File-set shall reside in the root directory of the directory hierarchy, and shall be named /DICOMDIR.;1.

Multiple DICOMDIR files shall not be stored on a single volume under this annex.