P.1 DICOM mapping to media format

P.1.1 Media Character Set

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

Notes: 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 PS 3.10) is a subset of the ISO 9660 character set, therefore no further restrictions need to be imposed for ISO 9660 filesystems.

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 subdirectories. Subdirectories may contain reference to both files and other subdirectories.

P.1.3.1 File ID

PS 3.10 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 PS 3.10.

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 PS 3.10.

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.