7.2 Data Set Encapsulation

Each File shall contain a single Data Set representing a single SOP Instance related to a single SOP Class (and corresponding IOD).


A file may contain more than a single 2D image frame as specific IODs may be defined to include multiple frames.

The Transfer Syntax used to encode the Data Set shall be the one identified by the Transfer Syntax UID of the DICOM File Meta Information.


  1. The Transfer Syntax used to encode the Data Set cannot be changed within the Data Set; i.e., the Transfer Syntax UID Data Element may not occur anywhere within the Data Set, e.g., nested within a Sequence Item.

  2. A DICOM Data Set does not include its total length. The end of the file indication provided by the DICOM File Service (see Section 8.4) is the only indication of the end of the Data Set.

The last Data Element of a Data Set may be Data Element (FFFC,FFFC) if padding of a Data Set is desired when a file is written. The Value of this Data Set Trailing Padding Data Element (FFFC,FFFC) has no significance and shall be ignored by all DICOM implementations reading this Data Set. File-set Readers or Updaters shall be able to process this Data Set Trailing Padding (FFFC,FFFC) either in the Data Set following the Meta Information or in Data Sets nested in a Sequence (see PS3.5).