DICOM PS3.3 2017e - Information Object Definitions

5.6 Invocation of Context Groups
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## 5.6 Invocation of Context Groups

The conventions used for Code Sequences are:

- no Baseline Defined

- using the Context Group as Baseline Context Group

- using the Context Group as Defined Context Group

See also “Codes and Controlled Terminology Definitions:” in PS3.16 .

In combination with the definition of the Context Group as Extensible or Non-extensible in PS3.16, the conventions in Table 5.6-1 apply.

Table 5.6-1. Conventions for Specification of Context Groups

| Extensible Context Group | Non-Extensible Context Group
--- | --- | ---
No Baseline or Defined CID specified | Any Code may be used if its meaning is applicable to the context of invocation.
Baseline Context Group Identifier (BCID) | Codes in the Context Group may be used. Alternative Codes for the same Concept (i.e., with the same meaning) may be used instead of the Codes in the Context Group, since this can be construed as not using the Baseline Context Group. Codes not in the Context Group may be used as an extension when their meaning is within the scope of that Context Group. I.e., any Code may be used if its meaning is applicable to the context of invocation. See also Section 7.2.3 “Extension of Context Groups” in PS3.16 . | Non-extensible Context Groups are not used as Baseline Context Groups.
Defined Context Group Identifier (DCID) | Codes in the Context Group shall be used. Codes not in the Context Group may be used as an extension to the specified Context Group when their meaning is within the scope of that Context Group. See also Section 7.2.3 “Extension of Context Groups” in PS3.16 . | Codes in the Context Group shall be used. Codes not in the Context Group shall not be used.

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DICOM PS3.3 2017e - Information Object Definitions