DICOM PS3.3 2020a - Information Object Definitions

F.3.2.2 Directory Information Module (Current)
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#### F.3.2.2 Directory Information Module

This Module contains a Sequence of Directory Records forming one or more Directory Entities. This Module defines at least one Directory Entity, the Root Directory Entity (which may be empty). Each Directory Record is composed of Directory Elements (marked by a ">"). They include:

1. an offset pointer to another Directory Record of the Same Directory Entity

2. an offset pointer to a lower level Directory Entity

3. a Referenced File pointed to by the Directory Record

4. a set of keys representative of the information contained in the Referenced File

Table F.3-3. Directory Information Module Attributes

Attribute Name | Tag | Type | Attribute Description
--- | --- | --- | ---
Offset of the First Directory Record of the Root Directory Entity | (0004,1200) | 1 | Offset of the first byte (of the Item Data Element) of the first Directory Record of the Root Directory Entity. This Offset is a number of bytes starting with the first byte of the File Meta Information. When the Root Directory Entity contains no Directory Record, this offset shall be set to 00000000H. ### Note This offset includes the File Preamble and the DICM Prefix.
Offset of the Last Directory Record of the Root Directory Entity | (0004,1202) | 1 | Offset of the first byte (of the Item Data Element) of the last Directory Record of the Root Directory Entity. This Offset is a number of bytes starting with the first byte of the File Meta Information. When the Root Directory Entity contains no Directory Record, this offset shall be set to 00000000H. ### Note This offset includes the File Preamble and the DICM Prefix.
File-set Consistency Flag | (0004,1212) | 1 | Enumerated Values: 0000H no known inconsistencies The value FFFFH shall never be present. ### Note Formerly, this Attribute was intended to signal that the directory was in an inconsistent state with a value of FFFFH. This usage has been retired. See PS3.3-2008.
Directory Record Sequence | (0004,1220) | 2 | Sequence of zero or more Items where each Item contains a Directory Record by including the Directory Elements from (0004,1400) to (0004,1511) and Record selection Keys as defined below (marked with a >). A zero length Value indicates that no Directory Records are contained in the Root Directory Entity.
>Offset of the Next Directory Record | (0004,1400) | 1 | Offset of the first byte (of the Item Data Element) of the next Directory Record of the same Directory Entity. This Offset is an unsigned integer representing a number of bytes starting with the first byte of the File Meta-information. A zero offset shall be used to mean that there is no other Directory Record in this Directory Entity. This Offset may be used to keep an inactive Record (0004,1410) chained with the next Directory Record of the same Directory Entity. ### Note This offset includes the File Preamble and the DICM Prefix.
>Record In-use Flag | (0004,1410) | 1 | Enumerated Values: FFFFH record is in use. The value 0000H shall never be present. ### Note Formerly, this Attribute was intended to facilitate the deletion of files, with a value 0000H signally an inactive record. This usage has been retired. See PS3.3-2008. Other Values are reserved and shall not be set by File-set Creators, but if present shall be interpreted as FFFFH by File-set Readers or Updaters.
>Offset of Referenced Lower-Level Directory Entity | (0004,1420) | 1 | Offset of the first byte (of the Item Data Element) of the first Directory Record of the Referenced Lower Level Directory Entity. This Offset is a number of bytes starting with the first byte of the File Meta Information. When no lower-level Directory Entity (containing at least one Directory Record) is referenced, this Attribute shall have a Value of 00000000H. ### Note This offset includes the File Preamble and the DICM Prefix.
>Directory Record Type | (0004,1430) | 1 | Defines a specialized type of Directory Record by reference to its position in the Media Storage Directory Information Model (see Section F.4). Enumerated Values: PATIENT STUDY SERIES IMAGE RADIOTHERAPY RT DOSE RT STRUCTURE SET RT PLAN RT TREAT RECORD PRESENTATION WAVEFORM SR DOCUMENT KEY OBJECT DOC SPECTROSCOPY RAW DATA REGISTRATION FIDUCIAL HANGING PROTOCOL ENCAP DOC VALUE MAP STEREOMETRIC PALETTE IMPLANT IMPLANT GROUP IMPLANT ASSY MEASUREMENT SURFACE SURFACE SCAN TRACT ASSESSMENT PRIVATE Privately defined record hierarchy position. Type shall be defined by Private Record UID (0004,1432). ### Note Enumerated Values PRINT QUEUE, FILM SESSION, FILM BOX, and IMAGE BOX were previously defined. They are now retired. See PS3.3-1998. Enumerated Values OVERLAY, MODALITY LUT, VOI LUT, CURVE, TOPIC, VISIT, RESULTS, INTERPRETATION, STUDY COMPONENT and STORED PRINT were previously defined. They are now retired. See PS3.3-2004. Enumerated Value MRDR was previously defined, to allow indirect reference to a File by multiple Directory Records. It is now retired. FSUs and FSRs are unlikely to be capable of supporting this mechanism. See PS3.3-2004. Enumerated Value HL7 STRUC DOC was previously defined. It is now retired. See PS3.3-2018b.
>Private Record UID | (0004,1432) | 1C | Required if the Directory Record Type (0004,1430) is of Value PRIVATE. This UID is used to define a non-standard type of Directory Record by reference to its position in a private extension to the Basic Directory IOD Information Model (see Section F.5). This UID shall be registered according to the procedures defined in PS3.5. Its meaning may or may not be specified in a Conformance Statement.
>Referenced File ID | (0004,1500) | 1C | A Multiple Value (see PS3.5) that represents the ordered components of the File ID containing a "referenced object" or Referenced SOP Instance. A maximum of 8 components, each from 1 to 8 characters shall be used (see Section 8.2). ### Note The Referenced File ID provides the means to "locate" the File through the DICOM File Service provided by the Media Format Layer. All referenced Files shall be with the File-set to which the Directory belongs. Any File within the File-set (to which the Directory belongs) shall be referenced by at most one Directory Record. When the Directory Record does not reference any SOP Instance this Attribute shall not be present.
>Referenced SOP Class UID in File | (0004,1510) | 1C | Unique ID for the SOP Class of the Instance stored in the referenced File. Required if the Directory Record references a SOP Instance.
>Referenced SOP Instance UID in File | (0004,1511) | 1C | Unique Identifier for the SOP Instance stored in the referenced file. Required if the Directory Record references a SOP Instance.
>Referenced Transfer Syntax UID in File | (0004,1512) | 1C | Unique Identifier for the Transfer Syntax used to encode the Instance stored in the referenced file. Required if the Directory Record references a SOP Instance.
>Referenced Related General SOP Class UID in File | (0004,151A) | 1C | Unique ID for the Related General SOP Class(es) related to the SOP Class of the Instance stored in the referenced file. Required if the Directory Record references a SOP Instance that encodes the Related General SOP Class UID (0008,001A). ### Note This may be useful to an FSR that does not support the SOP Class of the referenced Instance, but does support one of the Related General SOP Classes.
>Record Selection Keys | See F.5 | See F.5 | A number of DICOM Data Elements that contain specific keys defined for each type of Directory Record (0004,1430) defined in Section F.5.

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DICOM PS3.3 2020a - Information Object Definitions