原文：
Data Dictionary
This part of the standard contains the registry of all DICOM Data Elements and all DICOM Unique
Identifiers that are defined within the DICOM Standard.
這部分定義了大多數會使用的Group Tag和Element Tag的相關詞彙及所使用的VR等，如下圖所示。

原文：
Message Exchange
This Part of the DICOM Standard specifies the DICOM Message Service Element (DIMSE). The DIMSE defines an Application Service Element (both the service and protocol) used by peer DICOM Application Entities for the purpose of exchanging medical images and related information.
The DIMSE provides its services by relying on the DIMSE protocol. The DIMSE protocol defines the encoding rules necessary to construct Messages. A Message is composed of a Command Set (defined in this part of the DICOM Standard) followed by a conditional Data Set (defined in PS 3.5).