markdowned-datasheets/USB_PD_R3.2/02-glossary-and-info.md

<!-- page 26 -->
# Chapter 2. Glossary and Info

## 2.1. Conventions

### 2.1.1. Precedence

If there is a conflict between text, figures, and tables, the precedence is tables, figures, and then text.

### 2.1.2. Keywords

The following keywords differentiate between the various levels of a requirement and the applicable options.

**Table 2.1. Keywords**

| Keyword | Definition |
|---|---|
| Deprecated | Indicates a feature, supported in previous releases of the specification, which is no longer supported. |
| Discard / Discards / Discarded | Indicates that a Packet, when received, is thrown away by either the PHY Layer or the Protocol Layer. |
| Dynamic | Indicates a field or behavior that is not static and is allowed to change. |
| Ignore / Ignores / Ignored | Indicates a Message or Message field which, when received, results in no special action by the receiver.A Message with an Ignored field is processed normally except for any actions relating to the Ignored field. |
| Informative | Content provided to improve comprehension; not an implementation requirement. |
| Invalid | When used in relation to a Packet, indicates that the Packet's usage or fields fall outside of the defined specification usage.<br><br>When used in relation to an Explicit Contract, indicates that a previously established Explicit Contract can no longer be maintained by the Source.<br><br>When used in relation to individual K-codes or K-code sequences, indicates that the received Signaling falls outside of the defined specification.<br><br>When used in relation to a Message Field, indicates that a disallowed value was received.<br><br>Invalid usages, fields, K-codes, and values might change in future revisions of this specification. |
| May / May Not | Indicates a choice with no implied preference. |
| N/A | Indicates that a field or value is not applicable and has no defined value and is not to be checked or used by the recipient. |
| Optional | Describes features not mandated by this specification. If a PDUSB Device implements an Optional feature, then all Required parts of the feature Shall be implemented. |
| Reserved | Indicates bits, bytes, words, fields, and code values that might be used by future revisions of this specification. Reserved bits, bytes, words, or fields are set to zero by the sender and are ignored by the receiver. |
| Required | Describes a feature or behavior mandated by this specification; something that Shall be implemented. |
| Shall | Equivalent keywords indicating a mandatory requirement. Designers are mandated to implement all such requirements to ensure interoperability with other compliant devices. |
| Shall Not | Inverse of Shall indicating non-compliant operation. |
| Should | Indicates a flexibility of choice with a preferred alternative; equivalent to the phrase "it is recommended that…". |
| Should Not | Inverse of Should; equivalent to the phrase "it is recommended that implementations do not…". |
| Static | Indicates a field or behavior that never changes. |
| Valid | Inverse of Invalid indicating either a Packet or Signaling that fall within the defined specification or an Explicit Contract that can be maintained by the Source. |

<!-- page 27 -->
### 2.1.3. Numbering

Numbers that are immediately followed by a lowercase "b" (e.g., 01b) are binary values. Numbers that are immediately followed by an uppercase "B" are byte values. Numbers that are immediately followed by a lowercase "h" (e.g., 3Ah) or are preceded by "0x" (e.g., 0xFF00) are hexadecimal values. Numbers that do not contain any letters are decimal values.

## 2.2. Related Documents

Document references listed in Table 2.2 are inclusive of all approved and published ECNs and Errata.

**Table 2.2. Document References**

| Bookmark Reference | Title |
|---|---|
| [DPTC] | DisplayPort Alt Mode on USB Type-C Standard www.vesa.org. |
| [IEC 60950-1] | IEC 60950-1 Information technology equipment – Safety – Part 1: General requirements: Amendment 1:2009, Amendment 2:2013. www.iec.ch. |
| [IEC 60958-1] | IEC 60958-1 Digital Audio Interface Part:1 General. www.iec.ch. |
| [IEC 62368-1] | IEC 62368-1 Audio/Video, information, and communication technology equipment – Part 1: Safety requirements. www.iec.ch. |
| [ISO 3166] | ISO 3166 international Standard for country codes and codes for their subdivisions. www.iso.org/iso/home/standards/country_codes.htm. |
| [TBT3] | See [USB4] for Thunderbolt 3 Device operation www.usb.org/documents. |
| [UCSI] | USB Type-C Connector System Software Interface (UCSI) Specification www.usb.org/documents. |
| [USB2] | Universal Serial Bus 2.0 Specification, www.usb.org/documents. |
| [USB3] | Universal Serial Bus 3.2 Specification www.usb.org/documents. |
| [USB-C] | Universal Serial Bus Type-C Cable and Connector Specification, www.usb.org/documents. |
| [USB4] | Universal Serial Bus 4 Specification (USB4), www.usb.org/documents. |
| [USB BC] | Universal Serial Bus Battery Charging Specification plus Errata (referred to in this document as the Battery Charging specification). www.usb.org/documents. |
| [PD] | Universal Serial Bus Power Deliver Specification, Revsion 3.2 Version 1.2. www.usb.org/documents. |
| [PD2] | Universal Serial Bus Power Deliver Specification, Revsion 2.0 Version 1.3. www.usb.org/documents. |
| [PDSSR] | PDUSB Status Reporting and Device States, Revision 1.1. www.usb.org/documents. |
| [PDFU] | Universal Serial Bus Power Delivery Firmware Update Specification, Revision 1.0. www.usb.org/documents. |
| [USBC Auth] | Universal Serial Bus Type-C Authentication Specification, www.usb.org/documents. |
| [USBPD Compliance] | USB Power Delivery Compliance Test Specification, www.usb.org/documents. |
| [PDUSB] | PDUSB Status Reporting and Device States, Revision 1.1. www.usb.org/documents. |

## 2.3. Terms and Abbreviations

This section defines terms used throughout this document. For additional terms that pertain to the Universal Serial Bus, see Table 2.3 in the [USB2], [USB3], [USB-C] and [USB BC] specifications.

**Table 2.3. Terms and Abbreviations**

| Term | Description |
|---|---|
| AC Supply / AC Supplied | Refers to the main AC power Source typically provided to the wall and often referred to as "mains" or "wall mains". |

<!-- page 28 -->
| Term | Description |
|---|---|
| Active Cable | A cable with a USB Type-C plug on each end that incorporates data bus signal conditioning circuits. The cable supports the Structured VDM Discover Identity Command to expose its characteristics in addition to other Structured VDM Commands (Electronically Marked Cable see [USB-C]). |
| Active Cable VDO | VDO defining the Capabilities of an Active Cable. |
| Active Mode | A Mode which has been through the Mode Entry process but not the Mode Exit process. |
| Adjustable Voltage Supply (AVS) | A power supply whose output voltage can be adjusted to an operating voltage within its Advertised range inside an APDO. |
| Advertise | An offer for power made by a Source in the Source_Capabilities/EPR_Source_Capabilities Message (e.g., a PDO or APDO). |
| Alternate Mode | Operation defined by a Vendor or Standard's organization, which is associated with a SVID. The definition of Alternate Modes is outside the scope of USB-IF specifications. Entry to and exit from the Alternate Mode uses the Mode Entry and Mode Exit processes. |
| Alternate Mode Adapter (AMA) | A Device which supports Alternate Modes. |
| Alternate Mode Controller (AMC) | A Host that supports connection to AMAs. |
| Assured Capacity Port | Assured Capacity Port – As defined in [USB-C]. Assured Capacity Ports can be either Managed Capability Ports or Guaranteed Capability Ports. |
| Atomic Message Sequence (AMS) | A fixed sequence of Messages that must complete before other messages are allowed to be sent. |
| Attach / Attached / Attachment | Mechanical joining of the Port Pair by a connector. |
| Augmented Power Data Object (APDO) | Data Object used to expose a Source Port's or Sink Port's power Capabilities as part of a Source_Capabilities/EPR_Source_Capabilities or Sink_Capabilities/EPR_Sink_Capabilities Message respectively. A PPS Data Object, SPR AVS Data Object and EPR AVS Data Object are defined. |
| Battery | A power storage Device residing behind a Port that can either be a Source or Sink of power. |
| Battery Slot | A physical location where a Hot Swappable Battery can be installed. A Battery Slot might or might not have a Hot Swappable Battery present in a Battery Slot at any given time. |
| Battery Supply | A power supply that directly applies the output of a Battery to VBUS. This is exposed by the Battery Supply PDO. |
| Bi-phase Mark Coding (BMC) | Modification of Manchester coding where each zero has one transition and a one has two transitions (see [IEC 60958-1]). |
| Built-In Self-Test (BIST) | Power Delivery testing mechanism for the PHY Layer. |
| BIST Data Object (BDO) | Data Object used by BIST Messages. |
| BIST Mode | A BIST receiver or transmitter test Mode enabled by a BIST Message. |
| BIST Carrier Mode | A BIST Mode in which the PHY Layer sends out a BMC encoded continuous string of alternating "1"s and "0"s. |
| BIST Test Data Mode | A BIST Mode in which the PHY Layer sends out a GoodCRC Message and then enters a test Mode where it sends no further Messages, except GoodCRC Messages, in response to received Messages. |
| BIST Shared Capacity Test Mode | A BIST Mode applicable only to a Shared Capacity Group of Ports where the maximum Source Capabilities are always offered on every Port, regardless of the availability of shared power i.e., all shared power management is disabled. |
| Cable Capabilities | Capabilities offered by a Cable Plug. |
| Cable Discovered | USB Power Delivery Ports that have exchanged a Message and a GoodCRC Message response with a Cable Plug or a VPD using the USB Power Delivery protocol so that both the Port and the Cable Plug know that each is PD Capable and which Revision they each support. |
| Cable Discovery | See Cable Discovered. |
| Cable Plug | Term used to describe a PD Capable element in a Multi-Drop system addressed by SOP' Packets/ SOP'' Packets. Logically the Cable Plug is associated with a USB Type-C plug at one end of the cable. In a practical implementation, the electronics might reside anywhere in the cable. |
| Cable Reset | This is initiated by Cable Reset Signaling from the DFP. It restores the Cable Plugs to their default, power up condition and resets the PD communications engine in the cable to its default State. It does not reset the Port Partners. |
| Cable VDO | VDO returned by the Cable Plug containing Cable Capabilities. |
| Capabilities | Features supported by a product. These can include, for example, power levels supplied/ needed, cable type, Battery support or [USB4] support. |

<!-- page 29 -->
| Term | Description |
|---|---|
| Capabilities Mismatch | Indication from the Sink that the Source's Advertised Capabilities don't match the Sink's needs. |
| Configuration Channel (CC) | Single wire used by the BMC PHY Layer Signaling Scheme (see [USB-C]). |
| Cert Stat VDO | The Cert Stat VDO contains the XID assigned by USB-IF to the product before certification in binary format. |
| Charge-Through Accessory | A USB accessory that is designed to allow a Source to be Connected through the accessory to charge a system to which it is Attached. Most common use is to allow a single Port USB Host to support a USB Device while being charged through the accessory from and external Source. |
| Chunk | A 26 byte or less portion of a Data Block. Data Blocks can be sent either as a single Message or as a series of Chunks. |
| Chunked Extended Message | Extended Message which has been broken up into Chunks. |
| Chunking | The process of breaking up a Data Block larger than 26 bytes into two or more Chunks. |
| Chunking Layer | Part of the Protocol Layer responsible for Chunking. |
| Cold Socket | A Port that does not apply power on VBUS until a Sink is Attached. |
| Collision Avoidance | Mechanisms to prevent simultaneous communication by the Source, Sink and Cable Plug on CC. |
| Command | Request and response pair defined as part of a Structured Vendor Defined Message. |
| Connected / Connect | USB Power Delivery ports that have exchanged a Message and a GoodCRC Message response using the USB Power Delivery protocol so that both Port Partners know that each is PD Capable. |
| Constant Voltage (CV) | A Constant Voltage feature of a PPS Source. The PPS Source output voltage remains constant as the load changes up to its Current Limit. |
| Continuous BIST Mode | The BIST Mode where the Port or Cable Plug being tested sends a continuous stream of test data. |
| Contract | An agreement on both power level and direction between a Port Pair. A Contract could be explicitly Negotiated between the Port Pair or could be an implicit power level defined by the current State. While operating in Power Delivery Mode there will always be either an Explicit Contract or Implicit Contract in place. The Contract can only be altered in the case of a Negotiation/Re-Negotiation, Power Role Swap, Fast Role Swap, Hard Reset, Error Recovery or failure of the Source. |
| Control Message | A Control Message is defined as a Message with the Number of Data Objects field in the Message Header is set to zero. The Control Message consists only of a Message Header and a CRC. |
| Cyclic Redundancy Check (CRC) | An error-detecting code used to determine if a block of data has been corrupted. |
| Current Limit (CL) | A current limiting feature of a PPS Source. When a Sink operating in PPS Mode attempts to draw more current from the Source than the requested Current Limit value, the Source reduces its output voltage so the current it supplies remains at or below the requested value.<br><br>Note: Current Limit is not supported by SPR AVS and EPR AVS Sources. |
| Data Block | An Extended Message Payload data unit. This is distinct from a Data Object used by a Data Message which is always a 32-bit object. |
| Data Message | A Data Message consists of a Message Header followed by one or more Data Objects. Data Messages are easily identifiable because the Number of Data Objects field in the Message Header is always a non-zero value. |
| Data Object | A Data Message Payload data unit. This 32-bit object contains information specific to different types of Data Message. For example Power, Request, BIST, and Vendor Data Objects are defined. |
| Data Reset | Process which resets USB Communication. |
| Data Role | A Port Partner will be in one of two Data Roles; either DFP (USB Host) or UFP (USB Device). |
| Data Role Swap | Process of exchanging the Data Roles between Port Partners. |
| Dead Battery | A Device has a Dead Battery when the Battery in a Device is unable to power its functions. |
| Default Contract | An agreement on current at 5V is reached between a Port Pair based on Type-C current [USB-C]. |
| Detach / Detached | Mechanical unjoining of the Port Pair by removal of the cable. |
| Device | When in upper cased (Device), refers to a USB Device (Peripheral or Hub). When lower cased (device), it refers to any USB product, either USB Device or USB Host. |
| Device Policy | Policy applied across multiple Ports in a Source or Sink. |
| Device Policy Manager (DPM) | Module running in a Source or Sink that applies Device Policy to each Port in the Device, as Local Policy, via the Policy Engine. |
| DFP VDO | VDO returned by the DFP containing Capabilities. |

<!-- page 30 -->
| Term | Description |
|---|---|
| Differential Non-Linearity (DNL) | The difference between an ideal LSB step, and the real observable LSB step. A DNL of 0 indicates that the step is ideal. |
| Discovery Process | Command sequence using Structured Vendor Defined Messages resulting in identification of the Port Partner and Cable Plug, and their supported SVIDs and Alternate Modes. |
| Downstream Facing Port (DFP) | Indicates the Port's position in the USB topology which typically corresponds to a USB Host root Port or Hub downstream Port as defined in [USB-C]. At connection, the Port defaults to operation as the Source and as a USB Host (when USB Communication is supported). |
| Dual-Role Data (DRD) | Capability of operating as either a DFP or UFP. |
| Dual-Role Power (DRP) | Capability of operating as either a Source or Sink. |
| **Dynamic** Power Supply (DPS) | A Source that offers a guaranteed power and offers a maximum power when conditions are right. Conditions may include low enough internal temperature, ambient temperature, etc. The maximum power capability is not guaranteed and may be revoked by the Source. |
| End of Packet (EOP) | K-code marker used to delineate the end of a Packet. |
| Extended Power Range (EPR) | Extends the power range from a maximum of 100W (SPR) to a maximum of 240W (EPR). When operating in the EPR Mode, only EPR specific Messages (the EPR_Source_Capabilities Message and the EPR_Request Message) are used to Negotiate Explicit Contracts. |
| EPR AVS | A power supply operating in EPR Mode whose output voltage can be adjusted to an operating voltage within its Advertised range through an APDO. |
| EPR AVS Mode | A EPR Source, currently operating in an EPR AVS Contract, is said to be operating in EPR AVS Mode. |
| EPR Cable | A cable which is rated to operate in both SPR Mode and EPR Mode. |
| EPR Capabilities | The EPR Capabilities Messages (EPR_Source_Capabilities and EPR_Sink_Capabilities) are Extended Messages with the first seven positions filled with the same SPR PDOs and APDOs returned by the SPR Capabilities Messages (Source_Capabilities and Sink_Capabilities) followed by the EPR PDOs and APDOs starting in the eighth position. |
| EPR Capable | A product which has the ability to operate in EPR Mode. |
| EPR Mode | A Power Delivery Mode of operation where maximum allowable voltage is 48V. The Sink complies to the requirements of [IEC 62368-1] for operation with a PS3 Source. The Source complies to the requirements of [IEC 62368-1] for operation with a PS3 Sink. The cable complies with [IEC 62368-1]. Entry into the EPR Mode requires that an EPR Source is Attached to an EPR Sink with an EPR Cable. The EPR Source will only enter the EPR Mode when requested to do so by the Sink and it has determined it is Attached to an EPR Sink with an EPR Capable cable.<br><br>Only the EPR_Source_Capabilities and the EPR_Request Messages are allowed to Negotiate EPR Explicit Contracts. The SPR Mode Messages (Source_Capabilities and Request) are not allowed to be used while in EPR Mode. |
| EPR PDO / EPR APDO | Fixed Supply PDO that offers either 28V, 36V or 48V.<br><br>Adjustable Voltage Supply (AVS) APDO whose Maximum voltage is the highest Fixed Supply PDO voltage in the EPR_Source_Capabilities Message and no more than 240W. |
| EPR Sink | A Sink that supports both SPR Mode and EPR Mode. |
| EPR Source | A Source that supports both SPR Mode and EPR Mode. |
| Error Recovery | Port enters the ErrorRecovery State as defined in [USB-C]. |
| Explicit Contract | An agreement reached between a Port Pair as a result of the Power Delivery Negotiation process. An Explicit Contract is established (or continued) when a Source sends an Accept Message in response to a Request Message sent by a Sink followed by a PS_RDY Message sent by the Source to indicate that the power supply is ready. This corresponds to the PE_SRC_Ready State for a Source Policy Engine and the PE_SNK_Ready State for a Source Policy Engine. The Explicit Contract can be altered through the Re-Negotiation process. |
| Extended Capabilities | An Extended Message containing Capabilities information. |
| Extended Control Message | An Extended Message containing control information only. |
| Extended Message | A Message containing Data Blocks. The Extended Message is defined by the Extended field in the Message Header being set to one and contains an Extended Message Header immediately following the Message Header. |
| Extended Message Header | Every Extended Message contains a 16-bit Extended Message Header immediately following the Message Header containing information about the Data Block and any Chunking being applied. |

<!-- page 31 -->
| Term | Description |
|---|---|
| External Power Supply (EPS) | An AC Supplied Device that is only used to provide power as a Source (e.g. Power Brick). |
| External Supply | Power supply external to the Device. This could be powered from the wall or from any other power Source. |
| Fast Role Swap (FRS) | Process of exchanging the Source and Sink Power Roles between Port Partners rapidly due to the disconnection of an External Power Supply. |
| First Explicit Contract | The Explicit Contract that immediately follows an Attach, power on Hard Reset, Power Role Swap or Fast Role Swap event. |
| Fixed Battery | A Battery that is not easily removed or replaced by an end user e.g., requires a special tool to access or is soldered in. |
| Fixed Supply | A well-regulated fixed voltage power supply with a narrow variablility as described in a Fixed Supply PDO. |
| Frame | Generic term referring to an atomic communication transmitted by PD such as a Packet, Test Frame or Signaling. |
| Guaranteed Capability Port | A Guaranteed Capability Port is always capable of delivering its Port Maximum PDP and indicates this by setting its Port Present PDP to be the same as its Port Maximum PDP except when limited by the cable's Capabilities. This is a **Static** capability. |
| Hard Reset | This is initiated by Hard Reset Signaling from either Port Partner. It restores VBUS to USB Default Operation and resets the PD communications engine to its default State in both Port Partners as well as in any Attached Cable Plugs. It restores both Port Partners to their default Data Roles and returns the VCONN Source to the Source Port. A DRP Source Port operating as a Source will continue to operate as a Source. |
| Host | See USB Host. |
| Hot Swappable Battery | A Battery that is easily accessible for a user to remove or change for another Battery. |
| Hub | A USB Device that provides additional connections to the USB. |
| ID Header VDO | The VDO in a Discover Identity Command immediately following the VDM Header. The ID Header VDO contains information corresponding to the Power Delivery Product. |
| Idle | Condition on CC where there are no signal transitions within a given time window. |
| Implicit Contract | An agreement on power levels between a Port Pair which occurs, not because of the Power Delivery Negotiation process, but because of a Power Role Swap or Fast Role Swap. Implicit Contracts are transitory since the Port Pair is required to immediately Negotiate an Explicit Contract after the Power Role Swap. An Implicit Contract **Shall** be limited to Type-C current [USB-C]. |
| Initial Sink | Sink at the start of a Power Role Swap or Fast Role Swap which transitions to being the New Source. |
| Initial Source | Source at the start of a Power Role Swap or Fast Role Swap which transitions to being the New Sink. |
| Initiator | The initial sender of a Command Request in the form of a query. |
| Invariant PDOs | A Source Port that offers Invariant PDOs will always Advertise the same PDOs except when limited by the cable. |
| IoC | The Negotiated operating current. |
| IR Drop | The voltage drop across the cable and connectors between the Source and the Sink as defined in [USB-C]. It is a function of the resistance of the ground and power wire in the cable plus the contact resistance in the connectors times the current flowing over the path. |
| K-code | Special symbols provided by the 4b5b coding scheme. K-codes are used to signal Hard Reset and Cable Reset and delineate Packet boundaries. |
| Local Policy | Every PD Capable Device has its own Policy, called the Local Policy that is executed by its Policy Engine to control its power delivery behavior. The Local Policy at any given time might be the default Policy, hard coded or modified by changes in operating parameters or one provided by the system USB Host or some combination of these. The Local Policy Optionally can be changed by a System Policy Manager. |
| LPS | Limited Power Supply as defined in [IEC 62368-1]. |
| LSB | An abbreviation for Least Significant Bit. |
| Managed Capability Port | A Managed Capability Port can have its Port Present PDP set to a different value than its Port Maximum PDP. Its Port Present PDP value can be dynamic and change during normal operation. |
| Message | The Packet Payload consisting of a Message Header for Control Messages and a Message Header and data for Data Messages and Extended Messages. |

<!-- page 32 -->
| Term | Description |
|---|---|
| Message Header | Every Message starts with a 16-bit Message Header containing basic information about the Message and the PD Port's Capabilities. |
| Modal Operation | Operation where there are one or more Active Data Mode. Modal Operation ends when there are no longer any Active Data Modes. |
| Mode | Mode is a general term used to describe a particular type of operation of a given Device. Examples of modes are: Alternate Mode, EPR Mode, SPR Mode. |
| Mode Entry | Process to start operation in a particular Mode. |
| Mode Exit | Process to end operation in a particular Mode. |
| Multi-Drop | PD is a Multi-Drop system sharing the Power Delivery communication channel between the Port Partners and the cable. |
| Negotiate / Negotiated / Negotiation | The PD process whereby the Source Advertises its Capabilities, the Sink requests one of the Advertised Capabilities, and the Source acknowledges the Request, alters its output to satisfy the request and informs the Sink. The result of the Negotiation is an Explicit Contract. |
| New Sink | Sink at the end of a Power Role Swap or Fast Role Swap which has transition from being the Initial Source. |
| New Source | Source at the end of a Power Role Swap or Fast Role Swap which has transition from being the Initial Sink. |
| Packet | One entire unit of PD communication including a Preamble, SOP*, Payload, CRC and EOP. |
| Passive Cable | Cable with a USB plug on each end at least one of which is a Cable Plug supporting SOP' that does not incorporate data bus signal conditioning circuits. Supports the Structured VDM Discover Identity to determine its characteristics (Electronically Marked Cable see [USB-C]).<br><br>Note: This specification does not discuss Passive Cables that are not Electronically Marked. |
| Passive Cable VDO | VDO defining the Capabilities of a Passive Cable. |
| Payload | Data content of a Packet, provided to/from the Protocol Layer. |
| PD | USB Power Delivery. |
| PD Capable | A Port that supports USB Power Delivery. |
| PD Power (PDP) | The output power of a Source or input power of a Sink. |
| PD SID | Standard ID allocated to this specification by the USB Implementer's Forum. |
| PDP Rating | The PDP Rating is the Manufacturer declared PDP. The Source Port PDP Rating is the Port Maximum PDP and the Sink Port PDP Rating is the maximum PDP the Sink can utilize. |
| PDUSB | USB Device Port or USB Host Port that is both PD Capable and capable of USB Communication. See also PDUSB Host, PDUSB Device and PDUSB Hub. |
| PDUSB Device | A USB Device with a PD Capable UFP. A PDUSB Device is only addressed by SOP Packets. |
| PDUSB Host | A USB Host which is PD Capable on at least one of its DFPs. |
| PDUSB Hub | A Port expander USB Device with a UFP and one or more DFPs which is PD Capable on at least one of its Ports. A self-powered PDUSB Hub is treated as a USB Type-C Multi-Port Charger. |
| PDUSB Peripheral | A USB Device with a PD Capable UFP which is not a PDUSB Hub. A PDUSB Peripheral is only addressed by SOP Packets. |
| Peripheral | A physical entity that is Attached to a USB cable and is currently operating as a USB Device. |
| PHY Layer | The Physical Layer responsible for sending and receiving Messages across the USB Type-C CC wire between a Port Pair. |
| Policy | Policy is defined by the product maker and sets the behavior of PD Capable parts of the system and defines the Capabilities it Advertises, requests made to (re)Negotiate power and the responses made to requests received. |
| Policy Engine (PE) | The Policy Engine interprets the Device Policy Manager's input to implement Policy for a given Port and directs the Protocol Layer to send appropriate Messages. |
| Port | An interface typically exposed through a receptacle, or via a plug on the end of a hard-wired captive cable. USB Power Delivery defines the interaction between a Port Pair. |
| Port Pair | Two Attached PD Capable Ports. |
| Port Partner | A Contract is Negotiated between a Port Pair Connected by a USB cable. These ports are known as Port Partners. |
| Power Conductor | The wire that delivers power from the Source to Sink. For example, USB's VBUS. |

<!-- page 33 -->
| Term | Description |
|---|---|
| Power Data Object (PDO) | Data Object used to expose a Source Port's or Sink Port's power Capabilities as part of a Source_Capabilities / EPR_Source_Capabilities or Sink_Capabilities / EPR_Sink_Capabilities Message respectively. Fixed Supply, Variable Supply and Battery Supply Power Data Objects are defined; SPR Mode uses all four while EPR Mode uses only Fixed Supply and AVS PDOs. |
| Power Delivery Mode | Operation after a Contract has initially been established between a Port Pair. This Mode persists during normal Power Delivery operation, including after a Power Delivery Mode. Power Delivery Mode can only be exited by Detaching the Ports, applying a Hard Reset or by the Source removing power (except when the Initial Source removes power from VBUS during the Power Role Swap procedure). |
| Power Role | A Port Partner will be in one of two Power Roles; either Source or Sink. |
| Power Role Swap | Process of exchanging the Source and Sink Power Roles between Port Partners. |
| Power Rules | Define voltages and current ranges that are offered by compliant USB Power Delivery Sources and used by a USB Power Delivery Sink for a given value of PDP Rating. |
| PPS Mode | An SPR Source, currently operating as a Programmable Power Supply, is said to be operating in PPS Mode. |
| Preamble | Start of a transmission which is used to enable the receiver to lock onto the carrier. The Preamble consists of a 64-bit sequence of alternating 0s and 1s starting with a "0" and ending with a "1" which is not 4b5b encoded. |
| Product ID (PID) | 16-bit unsigned value assigned by the vendor for a product. |
| Product Type | Product categorization returned as part of the Discover Identity Command. |
| Product Type VDO | VDO identifying a certain Product Type in the ID Header VDO of a Discover Identity Command. |
| Product VDO | The Product VDO contains identity information relating to the product. |
| Programmable Power Supply (PPS) | A power supply, operating in SPR Mode, whose output voltage can be programmatically adjusted in small increments over its Advertised range and has a programmable output current fold back.The Capabilities are exposed by the SPR Programmable Power Supply APDO. |
| Protocol Error | An Unexpected Message during an Atomic Message Sequence. A Protocol Error during an AMS will result in either a Soft Reset or a Hard Reset. |
| Protocol Layer | The entity that forms the Messages used to communicate information between Port Partners. |
| PS1 / PS2 / PS3 | Classification of electrical power as defined in [IEC 62368-1]. |
| Power Sinking Device (PSD) | Sink which draws power but has no other USB or Alternate Mode communication function e.g., a power bank. |
| Ra | Prior to application of VCONN, a powered cable applies a pull-down resistor Ra on its VCONN pin. |
| Rd | Pull-down resistor on the USB Type-C CC wire used to indicate that the Port is a Sink [USB-C]. |
| Re-Attach | Attach of the Port Pair by a cable after a previous Detach. |
| Re-Negotiate / Re-Negotiated / Re-Negotiation | A process wherein one of the Port Partners wants to alter the Negotiated Contract. |
| Request | Message used by a Sink Port to Negotiate a Contract; refers to either a Request/EPR_Request Message. |
| Request Data Object (RDO) | Data Object used by a Sink Port to Negotiate a Contract as a part of a Request/EPR_Request Message. |
| Responder | The receiver of a Command Request sent by an Initiator that replies with a Command response. |
| Revision | Major release of the USB Power Delivery specification. Each Revision will have variousVersions associated with it. |
| Revision 1.0 | **Deprecated** major Revision of the USB Power Delivery Specification. |
| Revision 2.0 | Superseded major Revision of the USB Power Delivery Specification as defined in [PD2], with which this specification is compatible. |
| Revision 3.x | Current major Revisions of the USB Power Delivery Specification. |
| Rp | Pull-up resistor on the USB Type-C CC wire used to indicate that the Port is a Source (see [USB-C]). |
| Shared Capacity Port | As defined in [USB-C]. Shared Capacity Ports can only be Managed Capability Ports |
| Signaling | Physical mechanism of transmitting bits. |
| Sink | The Port consuming power from VBUS; most commonly a USB Device. |
| Sink/Source | A Sink with the additional capability to function as a Source. This corresponds to a Dual-Role Power Port with Rd asserted on its CC wire. |
<!-- page 34 -->
| Term | Description |
|---|---|
| Sink Capabilities | Capabilities wanted by a Sink. |
| Sink Port | Port operating as a Sink. |
| Sink Standby | During Sink Standby the Sink reduces its current draw to minimum current. |
| Sink with Accessory Support | A Sink that can source VCONN, but does not source VBUS [USB-C]. |
| Soft Reset | A process that resets the PD communications engine to its default State. |
| Start of Packet (SOP) | K-code marker used to delineate the start of a Packet. |
| SOP Communication | Communication using SOP Packets also implies that an AMS is being followed. |
| SOP Packet | A Power Delivery Packet which starts with an SOP. |
| SOP' Communication | Communication with a Cable Plug using SOP' Packets, also implies that an AMS is being followed. |
| SOP' Packet | Any Power Delivery Packet which starts with an SOP' used to communicate with a Cable Plug. |
| SOP'' Communication | Communication with a Cable Plug using SOP'' Packets, also implies that an AMS is being followed. |
| SOP'' Packet | Any Power Delivery Packet which starts with an SOP'' used to communicate with a Cable Plug when SOP' Packets are being used to communicate with the other Cable Plug. |
| SOP' | K-code marker used for communication between a Port and a Cable Plug. See also SOP. |
| SOP'' | K-code marker used for communication between a Port and a Cable Plug. See also SOP. |
| SOP* | Used to generically refer to K-code markers: SOP, SOP' and SOP''. See also SOP. |
| SOP* Communication | Communication using SOP* Packets, also implies an AMS is being followed. |
| SOP* Packet | A term referring to any Power Delivery Packet starting with either SOP, SOP', or SOP''. |
| Source | The Port supplying power over VBUS. |
| Source/Sink | A Source with the additional capability to act as a Sink. This corresponds to a Dual-Role Power Port with Rp asserted on its CC wire. |
| Source Capabilities | Capabilities offered by a Source. |
| Source Port | Port operating as a Source. |
| Standard Power Range (SPR) | Only the Source_Capabilities and the Request Messages are allowed to Negotiate SPR Explicit Contracts. The EPR Messages (the EPR_Source_Capabilities Message and the EPR_Request Message) are not allowed to be used while in SPR Mode. |
| SPR AVS | An SPR Source whose output voltage can be adjusted to an operating voltage within its Advertised range as exposed by the SPR AVS APDO. |
| SPR AVS Mode | A SPR Source, currently operating in an SPR AVS Contract, is said to be operating in SPR AVS Mode. |
| SPR Capabilities | An SPR Capabilities Message (Source_Capabilities Message or Sink_Capabilities Message) has at least one Power Data Object for 5V followed by up to 6 additional Power Data Objects. |
| SPR Contract | Explicit Contract Negotiated, in SPR Mode, based on SPR PDOs and APDOs. |
| SPR Mode | The classic Mode of PD operation where Explicit Contracts are Negotiated using SPR PDOs and APDOs. |
| SPR PDO / SPR APDO | A PDO offered in SPR Mode. |
| PPS Mode | A power supply, currently operating in a PPS Contract, is said to be operating in PPS Mode. |
| SPR Sink | A Sink which only supports SPR Mode and does not support EPR Mode. |
| SPR Source | A Source which only supports SPR Mode and does not support EPR Mode. |
| Standard ID (SID) | 16-bit unsigned value assigned by the USB-IF to a given industry standards organization's specification. |
| Standard or Vendor ID (SVID) | Generic term referring to either a VID or a SID. SVID is used in place of the phrase "Standard or Vendor ID." |
| State | PD State machine State. |
| Structured Vendor Defined Message (SVDM) | A Vendor Defined Message where the contents and usage of bits 14...0 of the VDM Header are defined by this specification. |
| SVDM Header | The VDM Header for a Structured Vendor Defined Message. |
| Swap Standby | During Swap Standby the Source does not drive VBUS and the Sink's current draw does not exceed a minimum current. |

<!-- page 35 -->
| Term | Description |
|---|---|
| System Policy | Overall System Policy generated by the system, broken up into the policies required by each Port Pair to affect the System Policy. It is programmatically fed to the individual devices for consumption by their Policy Engines. |
| System Policy Manager (SPM) | Module running on the USB Host. It applies the System Policy through communication with PD Capable Sinks and Sources that are also Connected to the USB Host via USB. |
| Test Frame | Frame consisting of a Preamble, SOP*, followed by test data. |
| Test Pattern | Continuous stream of test data in a given sequence . |
| Tester | The Tester is assumed to be a piece of test equipment that manages the BIST testing process of a PD UUT. |
| Upstream Facing Port (UFP) | Indicates the Port's position in the USB topology typically a Port on a Device as defined in [USB-C]. At connection, the Port defaults to operation as a USB Device (when USB Communication is supported) and as a Sink. |
| UFP VDO | VDO returned by the UFP containing Capabilities. |
| Unit Interval (UI) | The time to transmit a single data bit on the wire. |
| Unchunked | See Unchunked Extended Message. |
| Unchunked Extended Message | Extended Message that has been transmitted whole without using Chunking. |
| Unexpected Message | Message that a Port supports but has been received in an incorrect State. |
| Unit Under Test (UUT) | The PD Device that is being tested by the Tester and responds to the initiation of a particular BIST test sequence. |
| Unrecognized Message | Message that a Port does not understand e.g., a Message using a **Reserved** Message type, a Message defined by a higher specification Revision than the Revision this Port supports, or an Unstructured Vendor Defined Message for which the VID is not recognized. |
| Unstructured Vendor Defined Message (UVDM) | A Vendor Defined Message where the contents of bits 14...0 of the VDM Header are undefined. |
| UVDM Header | The VDM Header for an Unstructured Vendor Defined Message. |
| Unsupported Message | Message that a Port recognizes but does not support. This is a Message defined by the specification, but which is not supported by this Port. |
| USB Attached State | Synonymous with the [USB2] and [USB3] definition of the Attached State |
| USB Communication | Transfer of USB data Packets as defined in [USB2] and [USB3]. |
| USB Default Operation | Operation of a Port at Attach or after a Hard Reset where the DFP Source applies 5V on VBUS and the UFP Sink is operating at 5V as defined in [USB2], [USB3], [USB-C] or [USB BC]. |
| USB Device | Either a Hub or a Peripheral Device as defined in [USB2], [USB3] and [USB4]. |
| USB Host | The system where the USB Host controller is installed as defined in [USB2], [USB3] and [USB4]. |
| USB Powered State | Synonymous with the [USB2] and [USB3] definition of the powered State. |
| USB Safe State | State of the USB Type-C connector when there are pins to be re-purposed (see [USB-C]) so they are not damaged by and do not cause damage to their Port Partner. |
| USB Type-A | Term used to refer to any A plug or receptacle including USB Micro-A plugs and USB Standard- A plugs and receptacles. USB Micro-AB receptacles are assumed to be a combination of USB Type-A and USB Type-B. |
| USB Type-B | Terms used to refer to any B-plug or receptacle including USB Mini-B plugs, USB Micro-B plugs, and USB Standard-B plugs and receptacles, including the PD and non-PD versions. USB Micro-AB receptacles are assumed to be a combination of USB Type-A and USB Type-B. |
| USB Type-C / USB-C | Term used to refer to the USB Type-C connector plug, or receptacle as defined in [USB-C]. |
| USB Type-C Multi-Port Charger | A product that exposes multiple USB Type-C Source Ports for the purpose of charging multiple Connected USB Devices as defined in [USB-C]. |
| USB-C Port Control | Module in a PD Capable Device which controls Attach/Detach and either detects or sets the Rp value and contains the USB Type-C State machines. |
| USB4 Mode | Device is operating in a Mode as defined in [USB4]. |
| Variable Supply | A power supply that has an output voltage that varies beyond the Fixed Supply range. This is exposed by the Variable Supply PDO. |
| VBUS | The VBUS wire delivers power from a Source to a Sink. |

<!-- page 36 -->
| Term | Description |
|---|---|
| VCONN | Once the connection between USB Host and Device is established, the CC pin (CC1 or CC2) in the receptacle that is not Connected via the CC wire through the standard cable is re-purposed to Source VCONN to power circuits in a Cable Plug, VCONN Powered Accessory or VCONN Powered USB Device (see [USB-C]). |
| VCONN Powered Accessory (VPA) | An accessory that is powered from VCONN to operate in an Alternate Mode (see [USB-C]). |
| VCONN Powered USB Charge Through Device (CT-VPD) | A CT-VPD is a VPD with an additional Port for connecting a Source (e.g., a Charger) as defined in [USB-C]. |
| VCONN Powered USB Device (VPD) | A captive cable USB Device that can be powered by either VCONN or VBUS as defined in [USB-C]. The term VPD refers to either a VPD or a CT-VPD with no Charger Connected. |
| VCONN Source | The USB Type-C Port responsible for sourcing VCONN. |
| VCONN Swap | Process of exchanging the VCONN Source between Port Partners. |
| Vendor Defined Message (VDM) | PD Data Message defined for vendor/standards usage. These are further partitioned into Structured Vendor Defined Messages, where Commands are defined in this specification, and Unstructured Vendor Defined Messages which are entirely vendor defined. |
| VDM Header | The first Data Object following the Message Header in a Vendor Defined Message. |
| VDO | See Vendor Data Object. |
| Vendor Data Object | Data Object used to send Vendor specific information as part of a Message. |
| Vendor Defined Extended Message (VDEM) | PD Extended Message defined for vendor/standards usage. A VDEM does not define any structure and Messages can be created in any manner that the vendor chooses. |
| Vendor ID (VID) | 16-bit unsigned value assigned by the USB-IF to a given Vendor. |
| Version | A minor release of the USB Power Delivery specification associated with a particular Revision. Version numbers are also defined in VDMs. |
| VI | Same as power (i.e., voltage × current = power) |