OSI/MHS Configuration and Management Manual

OSI/MHS Configuration and Management Manual—424827-003
Glossary-22
P3 protocol. The X.400 message submission and delivery protocol, which defines a
standard for the submission and delivery of messages and the interaction of UAs and
MTAs.
P7 protocol. The X.400 protocol defining access to the message store by remote or local
user agents.
package. A set of GPI object classes that are grouped together because they are
functionally related and defined in the same specification. For example, the MH 88
package consists of the message handling classes defined in the XAPIA specification.
packet switching. A technique in which messages are broken into smaller units, called
“packets,” which can be individually addressed and routed through the network. The
receiving-end node ascertains that all the packets are received and in the proper
sequence before forwarding the complete message to the addressee.
PAM. See Port Access Method.
password server. An application process that provides security services at the
MTA-MTA or UA-MS boundary. Such an application uses either the MTA-bind or the
MS-bind password server interface of OSI/MHS. The master password server
provided with OSI/MHS is an example of a password server.
PDU (protocol data unit). An information unit that contains control and address information
and possibly data, and is exchanged between peer entities. Two types of PDUs
relevant to X.400 are:
PDU ID. An identifier generated by OSI/MHS for internal use. A PDU ID is not the same as
the MPDU ID defined by X.400.
PDU store. The database that stores messages in an X.400 system. A PDU store consists
of a data file and a log file. Each MR, MS, RS, and LO group has its own PDU store.
Physical Layer. Layer 1 in the OSI Reference Model. This layer establishes the actual
physical connection between the network and the computer equipment. Protocols at
the Physical Layer include rules for the transmission of bits across the physical
medium and rules for connectors and wiring.
Port Access Method (PAM). An HP NonStop communications subsystem that provides an
independent interface to allow applications access to token-ring or Ethernet local area
networks (LANs) on NonStop S-series servers. The PAM subsystem provides a port
interface that applications can use by making file-system procedure calls. The PAM
MPDU (message PDU) Information exchanged between message handling
systems (used by OSI/MHS)
APDU (application PDU) Information exchanged between OSI Application Layer
entities (used by OSI/AS)