9.3.2.2 Presentation context item structure

The Presentation Context Item shall be made of a sequence of mandatory fixed length fields followed by a variable field. Table 9-13 shows the sequence of the mandatory fields.

The variable field shall consist of one Abstract Syntax Sub-Item followed by one or more Transfer Syntax Sub-Items.

Table 9-13 PRESENTATION CONTEXT ITEM FIELDS

Item bytes Field name Description of field
1 Item-type 20H
2 Reserved This reserved field shall be sent with a value 00H but not tested to this value when received.
3-4 Item-length This Item-length shall be the number of bytes from the first byte of the following field to the last byte of the last Transfer Syntax Item. It shall be encoded as an unsigned binary number.
5 Presentation- context-ID Presentation-context-ID values shall be odd integers between 1 and 255, encoded as an unsigned binary number. For a complete description of the use of this field see Section 7.1.1.13.
6 Reserved This reserved field shall be sent with a value 00H but not tested to this value when received.
7 Reserved This reserved field shall be sent with a value 00H but not tested to this value when received.
8 Reserved This reserved field shall be sent with a value 00H but not tested to this value when received.
9-xxx Abstract/Transfer Syntax Sub-Items This variable field shall contain the following sub-items: one Abstract Syntax and one or more Transfer Syntax(es). For a complete description of the use and encoding of these sub-items see Sections 9.3.2.2.1 and 9.3.2.2.2.

9.3.2.2.1 Abstract syntax sub-item structure

The Abstract Syntax Sub-Item shall be made of a sequence of mandatory fixed length fields followed by a variable field. Table 9-14 shows the sequence of the mandatory fields.

Table 9-14 ABSTRACT SYNTAX SUB-ITEM FIELDS

Item bytes Field name Description of field
1 Item-type 30H
2 Reserved This reserved field shall be sent with a value 00H but not tested to this value when received.
3-4 Item-length This Item-length shall be the number of bytes from the first byte of the following field to the last byte of the Abstract-syntax-name field. It shall be encoded as an unsigned binary number.
5-xxx Abstract-syntax-name This variable field shall contain the Abstract-syntax-name related to the proposed presentation context. A valid Abstract-syntax-name shall be encoded as defined in Annex F. For a description of the use of this field see Section 7.1.1.13. Abstract-syntax-names are structured as UIDs as defined in PS 3.5 (see Annex B for an overview of this concept). DICOM Abstract-syntax-names are registered in PS 3.4.

9.3.2.2.2 Transfer syntax sub-item structure

The Transfer Syntax Sub-Item shall be made of a sequence of mandatory fixed length fields followed by a variable field. Table 9-15 shows the sequence of the mandatory fields.

Table 9-15 TRANSFER SYNTAX SUB-ITEM FIELDS

Item bytes Field name Description of field
1 Item-type 40H
2 Reserved This reserved field shall be sent with a value 00H but not tested to this value when received.
3-4 Item-length This Item-length shall be the number of bytes from the first byte of the following field to the last byte of the Transfer-syntax-name field(s). It shall be encoded as an unsigned binary numbers
5-xxx Transfer-syntax-name(s) This variable field shall contain the Transfer-syntax-name proposed for this presentation context. A valid Transfer-syntax-name shall be encoded as defined in Annex F. For a description of the use of this field see Section 7.1.1.13. Transfer-syntax-names are structured as UIDs as defined in PS 3.5 (see Annex B for an overview of this concept). DICOM Transfer-syntax-names are registered in PS 3.5.