A header that is added to a DICOM Instance when it is saved to file. The DICOM Meta information header is not part of the DICOM Instance itself. It adds information required for parsing the file correctly and identifying the application that saved the file.

The DICOM file meta info was added to the standard in part 10. That’s why DICOM Files that includes the meta info header are sometimes called ‘part 10 DICOM files’.
The DICOM File Meta Information Header is added as a group of DICOM tags with the group id (0002).

The header includes:
1) A preamble: 128 bytes with value 0x00
2) The DICOM Magic Number: 4 bytes with value “DICM”
3) Group (0002) data elements encoded using Little Endian Explicit

Within the group (0002) one of the elements is the Transfer Syntax UID (0002,0010) that determines the transfer syntax used for all the elements after group (0002).

Group (0002) also includes the Implementation Class UID and Implementation Version Name of the application that wrote the file.