P 120 mm DVD Medium (Normative)
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# P 120 mm DVD Medium (Normative)

This Annex defines the use of the UDF and ISO 9660 file systems with DVD media in such a manner as to require a reader to be capable of reading all of the physical media types and UDF and ISO 9660 file system versions that are defined in this Annex, and a creator to be able to create at least one of those types of media and file system.

The media types supported are DVD-ROM, DVD-R authoring and general, DVD-RW, DVD+R and DVD+RW.

### Note

1. Capitalization in this annex may be inconsistent with other DICOM standards in order to be consistent with historical usage for terms in referenced documents.

2. Mandatory support for reading both UDF and ISO 9660 is included to facilitate migration from legacy CD-R implementations, which use ISO 9660, as well as to support the industry standard file system for DVD, UDF.

Universal Disk Format (UDF) is a profile of the ECMA 167 3rd edition file system.

### Note

1. The ECMA 167 3rd edition is more recent than ISO 13346:1995, which is equivalent to ECMA 167 2nd edition.

2. A reader of a UDF 2.01 file system can also read a 2.0, 1.5 or 1.02 file system.

## P.1 DICOM Mapping to Media Format

### P.1.1Media Character Set

The character set used in UDF fields shall be the CS0 OSTA Compressed Unicode character set, required by the UDF standard.

### Note

1. The CS0 OSTA Unicode character set is defined in UDF and is a subset of Unicode 2.0.

2. UDF defines a specific form of compression of 8 and 16 bit Unicode characters that must be supported.

3. The character set defined elsewhere in this section for DICOM File-set fields is a subset of this character set. However other fields in the UDF file system, and other files in the UDF file system not in the DICOM File-set, may use characters beyond those defined by DICOM for File ID Components, including those encoded in 16 bits.

4. The character set for File IDs and File-set IDs (see PS3.10) is a subset of the ISO 9660 character set, therefore no further restrictions need to be imposed for ISO 9660 file systems.

### P.1.2 DICOM File-set

One and only one DICOM File-set shall be stored on each side of a single piece of media.

A DICOM File-set is defined to be completely contained within one UDF or ISO 9660 File-set.

Only a single UDF or ISO 9660 File-set shall be present in the UDF Volume.

Each side of the media will comprise a single self-contained UDF or ISO 9660 Volume. That is the UDF or ISO 9660 Volume Set shall not consist of more than one UDF or ISO 9660 Volume.

Only a single UDF or ISO 9660 Partition shall be present on each side the media.

### Note

Other partitions containing other file systems, possibly sharing the same data, may be present, such as an ISO-9660 bridge disk, a Mac HFS or Unix UFS hybrid disk, etc.

### P.1.3 DICOM File ID Mapping

The UDF and ISO 9660 Standards provide a hierarchical structure for directories and files within directories. Each volume has a root directory that may contain references to both files and sub-directories. Sub-directories may contain reference to both files and other sub-directories.

#### P.1.3.1 File ID

PS3.10 defines a DICOM File ID Component as a string of 8 characters from a subset of the G0 repertoire of ISO 8859. Each of these File ID Components is mapped to a UDF File Identifier or Path Component in the OSTA CS0 character set.

### Note

This mapping is a subset of the MS-DOS mapping specified in UDF.

Filename extensions are not used in DICOM File ID Components, hence an UDF or ISO 9660 File Identifier shall not contain a File Extension or the '.' that would precede such a File Extension.

The maximum number of levels of a Resolved Pathname in a UDF or ISO 9660 file-set shall be at most 8 levels, to comply with the definition of a DICOM File-set in PS3.10.

The File Version Number is always equal to 1, as specified by UDF or ISO 9660.

### Note

This file ID mapping is also compatible with ISO 9660 Level 1.

#### P.1.3.2 DICOMDIR File

A DICOMDIR file in a DICOM File-set shall reside in the root directory of the directory hierarchy, as specified in PS3.10.

### P.1.4 DICOM File Management Information

No file management information beyond that specified in the UDF or ISO 9660 File Entry is required. In particular no Extended Attributes or Named Streams are required.

### Note

Unlike the Annex of this part specifying CD-R media, no restrictions or specifications with respect to ISO 9660 Recording Date and Time, file modification date, file owner identification and permissions, or other Extended Attribute Record values are specified, since these may be beyond the control of the DICOM application.

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