The value of Context Identifier (0008,010F) identifies the Context Group defined by Mapping Resource (0008,0105) from which the values of Code Value (0008,0100) (or Long Code Value (0008,0119) or URN Code Value (0008,0120)) and Code Meaning (0008,0104) were selected, or to which Code Value (0008,0100) (or Long Code Value (0008,0119) or URN Code Value (0008,0120)) and Code Meaning (0008,0104) have been added as a private Context Group extension (see Section 8.7). The Context Identifier (0008,010F) Attribute uses VR CS, and for Context Groups defined in PS3.16 the value shall be the Context Group Identifier as a string of digits without leading zeros, and does not include the string "CID".

The value of Context UID (0008,0117) uniquely identifies the Context Group. See PS3.6.