DICOM Application Entities (AEs) that extend or replace the default repertoire convey this information in the Specific Character Set (0008,0005) Attribute.
Note: The Attribute Specific Character Set (0008,0005) is encoded using a subset of characters from ISO-IR 6. See the definition for the Value Representation (VR) of Code String (CS) in Table 6.2.1.
For Data Elements with Value Representations of SH (Short String), LO (Long String), ST (Short Text), LT (Long Text), PN (Person Name) or UT (Unlimited Text) the default character repertoire may be extended or replaced (these Value Representations are described in more detail in Section 6.2). If such an extension or replacement is used, the relevant "Specific Character Set" shall be defined as an attribute of the SOP Common Module (0008,0005) (see PS 3.3) and shall be stated in the Conformance Statement. PS 3.2 gives conformance guidelines.
Note: 1. Preferred repertoires as defined in ENV 41 503 and ENV 41 508 for the use in Western and Eastern Europe, respectively, are: ISO-IR 100, ISO-IR 101, ISO-IR 144, ISO-IR 126. See Section 18.104.22.168.
2. Information Object Definitions using different character sets cannot rely⎯per se⎯ on lexical ordering or string comparison of data elements represented as character strings. These operations can only be carried out within a given character repertoire and not across repertoire boundaries.