DICOM differs from other data formats in that it groups information together into a data set. That is, an X-Ray of your chest is in the same file as your patient ID, so that the image is never mistakenly separated from your information. It also mandates the presence of a media directory, the DICOMDIR file, that provides index and summary information for all the DICOM files on the media.

DICOM restricts the filenames on DICOM media to 8 character names (sometimes 8.3). This is a common source of problems with media created by developers that did not read the specifications carefully. This is a historical requirement to maintain compatibility with older existing systems. The DICOMDIR information provides substantially greater information about each file than any filename could, so there is less need for meaningful file names. Inexperienced developers also tend to make mistakes regarding the various mandatory and optional information fields and format restrictions on files.

The first significant DICOM standard is version 3.0, which was developed in 1993. Details of the DICOM specification are available at the NEMA site, and many public domain and open source implementations exist. There is also an ongoing media exchange test and connectathon process for CD media that is organized by the IHE organization.