PDU Items and Sub-items (pynetdicom.pdu_items)

ApplicationContextItem	An Application Context Item.
PresentationContextItemRQ	A Presentation Context (RQ) Item.
PresentationContextItemAC	A Presentation Context (AC) Ttem.
UserInformationItem	A User Information Item.
AbstractSyntaxSubItem	An Abstract Syntax Sub-item.
TransferSyntaxSubItem	A Transfer Syntax Sub-item.
MaximumLengthSubItem	A Maximum Length Sub-item.
ImplementationClassUIDSubItem	An Implementation Class UID Sub-item.
ImplementationVersionNameSubItem	An Implementation Version Name Sub-item.
SCP_SCU_RoleSelectionSubItem	An SCP/SCU Role Selection Sub-item.
AsynchronousOperationsWindowSubItem	An Asynchronous Operations Window Sub-item.
UserIdentitySubItemRQ	A User Identity (RQ) Sub-item.
UserIdentitySubItemAC	A User Identity (AC) Sub-item.
SOPClassExtendedNegotiationSubItem	A SOP Class Extended Negotiation Sub-item.
SOPClassCommonExtendedNegotiationSubItem	A SOP Class Common Extended Negotiation Sub-item.
PresentationDataValueItem	A Presentation Data Value Item.

The encoding of DICOM Upper Layer PDU Items and Sub-items is always Big Endian byte ordering.