pynetdicom.pdu_items.PresentationContextItemRQ

class pynetdicom.pdu_items.PresentationContextItemRQ

A Presentation Context (RQ) Item.

Presentation Contexts (RQ) Items are used by the association requestor to propose Abstract Syntaxes (specifications of data elements with associated semantics) and Transfer Syntaxes (sets of encoding rules).

Notes

A Presentation Context (RQ) Item requires the following parameters:

• Item type (1, fixed value, 0x20)

• Item length (1)

• Presentation context ID (1)

• Abstract/Transfer Syntax Sub-items (1)

  • Abstract Syntax Sub-item (1)

    • Item type (1, fixed, 0x30)

    • Item length (1)

    • Abstract syntax name (1)

  • Transfer Syntax Sub-items (1 or more)

    • Item type (1, fixed, 0x40)

    • Item length (1)

    • Transfer syntax name(s) (1 or more)

Encoding

When encoded, a Presentation Context (RQ) Item has the following structure, taken from Part 8, Table 9-13 of the DICOM Standard (offsets shown with Python indexing). Items are always encoded using Big Endian.

Offset	Length	Description
0	1	Item type
1	1	Reserved
2	2	Item length
4	1	Presentation context ID
5	1	Reserved
6	1	Reserved
7	1	Reserved
8	Variable	Abstract/transfer syntax sub-items

References

• DICOM Standard, Part 8, Annex B

• DICOM Standard, Part 8, Section 9.3.2.2

• DICOM Standard, Part 8, Section 9.3.1

__init__() → None

Initialise a new Presentation Context (RQ) Item.

Methods

__init__()	Initialise a new Presentation Context (RQ) Item.
decode(bytestream)	Decode bytestream and use the result to set the field values of the PDU item.
encode()	Return the encoded PDU as bytes.
from_primitive(primitive)	Set the item's values using a Presentation Context primitive.
to_primitive()	Return a PresentationContext primitive from the current Item.

Attributes

abstract_syntax	Return the Abstract Syntax, if available.
context_id	Return the item's Presentation Context ID field value as int.
item_length	Return the item's Item Length field value as int.
item_type	Return the item's Item Type field value as int.
transfer_syntax	Return the Transfer Syntax(es).

property abstract_syntax: UID | None

Return the Abstract Syntax, if available.

Return type:

pydicom.uid.UID or None

property context_id: int | None

Return the item’s Presentation Context ID field value as int.

from_primitive(primitive: PresentationContext) → None

Set the item’s values using a Presentation Context primitive.

Parameters:

primitive (presentation.PresentationContext) – The primitive to use to set the Item’s field values.

property item_length: int

Return the item’s Item Length field value as int.

to_primitive() → PresentationContext

Return a PresentationContext primitive from the current Item.

Returns:

The primitive representation of the current Item.

Return type:

presentation.PresentationContext

property transfer_syntax: List[UID]

Return the Transfer Syntax(es).

Return type:

list of pydicom.uid.UID