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MPAI-MMC adopts the following conventions:
- Words beginning with a capital letter are defined in Table 1.
- Words beginning with a small letter have the normal meaning consistent with the relevant context.
In Table 1 and Table 2, a dash “-” preceding a Term (first column) means the following:
- If the font of the Term is normal, the Term in the table without a dash and preceding the one with a dash should be placed before that Term. The notation is used to concentrate in one place all the Terms that are composed of, e.g., the word Audio followed by one of the words Object, Scene, and Scene Descriptors.
- If the font of the Term is italic, the Term in the table without a dash and preceding the one with a dash should be placed after that Term. The notation is used to concentrate in one place all the Terms that are composed of, e.g., the word Attitude preceded by one of the words Social or Spatial.
Table 1 – MPAI-PAF-specific Terms and Definitions
| Term | Definition |
| Attitude | |
| – Social | A Factor of the Personal Status related to the way a human or Avatar intends to position vis-à-vis the Environment or subsets of it, e.g., “Respectful”, “Confrontational”, “Soothing”. |
| – Spatial | Position and Orientation and their velocities and accelerations of a Human and Physical Object in a Digital Environment. |
| Audio | Digital representation of an analogue audio signal sampled at a frequency between 8-192 kHz with a number of bits/sample between 8 and 32, and non-linear and linear quantisation. |
| Authentication | The process of determining whether a device or a `human is what it states it is. |
| Avatar | A rendered Digital Human. |
| – Model | An inanimate Avatar exposing animation interfaces. |
| – Portable | A Data Type including Avatar ID, Time, Audio-Visual Scene Descriptors, Spatial Attitude, Avatar Model, Body Descriptors, Face Descriptors, Language Preference, Speech Coding, Speech Data, Text, and Personal Status. |
| Body | A digital representation of a human body, head included, face excluded. |
| Centre Point | The point of an Object selected to have Local Coordinates (0,0,0). |
| Cognitive State | An element of the internal status reflecting the way a human or avatar understands the Environment, such as “Confused”, “Dubious”, “Convinced”. |
| Context | The semantics of the information emitted by an Entity or included in its surrounding Scene. |
| Data | Information in digital form. |
| – Format | The syntax and semantics of a Data Type. |
| – Type | A particular type of Data. |
| Descriptor | The Digital Representation of a feature of an Object. |
| – Body | A Data Type including the digital representation of the features of the body of a real or digital human. |
| – Face | A Data Type including the digital representation of a feature of the face of a real or digital human. |
| Device | A piece of equipment used to interact and have Experience in a Digital Environment. |
| Digital Representation | Data corresponding to and representing a physical entity. |
| Emotion | The coded representation of the internal state resulting from the interaction of a human or avatar with the Environment or subsets of it, such as “Angry”, “Sad”, “Determined”. |
| Entity | A human in a real environment or digitally represented as a Digitised Human in a Virtual Environment a Digital or a Virtual Human in a Virtual Environment. |
| Environment | A Virtual Space that may be null or may include an Audio-Visual Scene. |
| Experience | The state of a human whose senses are continuously affected for a meaningful period. |
| Face | A digital representation of a human face. |
| Factor | One of Emotion, Cognitive State, and Spatial Attitude. |
| Gesture | A movement of a Digital Human or part of it, such as the head, arm, hand, and finger, often a complement to a vocal utterance. |
| Grade | The intensity of a Factor. |
| Human | |
| Digital | A Digitised or a Virtual Human in a Virtual Space. |
| Digitised | An Object in a Virtual Space that has the appearance of a specific human when rendered. |
| Virtual | An Object in a Virtual Space created by a computer that has a human appearance when rendered but is not a Digitised Human. |
| Identifier | The label uniquely associated with a human or an Object. |
| Modality | One of Text, Speech, Face, or Gesture. |
| Object | A data structure that can be rendered to cause an Experience. |
| – Audio | Coded representation of Audio information with its metadata. An Audio Object can include other Audio Objects. |
| – Audio-Visual | Coded representation of Audio-Visual information with its metadata. |
| – Descriptor | The digital representation of the feature of an Object. |
| – Digital | A Digitised or a Virtual Object. |
| – Digitised | The digital representation of a real object. |
| – Visual | Coded representation of Visual information with its metadata. A Visual Object can include other Visual Objects. |
| – Virtual | An Object not representing an object in a Real Environment. |
| Orientation | The 3 Euler angles of an Object in a Virtual Space. |
| Personal Status | A Data Type including three Factors – Cognitive State, Emotion and Social Attitude – conveyed by four Modalities – Text, Speech, Face, and Gesture and providing standard extensible labels for the three Factors. |
| Point of View | The Spatial Attitude of a Digital Human watching an Environment. |
| Portable Avatar | A Data Type representing an Avatar and its Context. |
| Position | The coordinates of a representative point for an object in a Virtual Space with respect to a set of coordinate axes. |
| Rendering | The process of instantiating a Virtual Space as a human-perceptible entity. |
| Scene | A Digital Environment populated by Objects. |
| – Audio | The Audio Objects of an Environment with Object metadata such as Spatial Attitude. |
| – Audio-Visual | (AV Scene) The Audio-Visual Objects of an Environment Object metadata such as Spatial Attitude. |
| – Visual | The Visual Objects of an Environment with Object metadata such as Spatial Attitude. |
| Scene Descriptors | The digital representation of a feature of a scene. |
| – Audio | A Data Type including the digital representation of the audio features of a real or digital scene. |
| – Audio-Visual | A Data Type combining the Audio or Visual Scene Descriptors. |
| – Visual | A Data Type including the digital representation of the visual features of a real or digital scene. |
| Representation | Data that digitally represents an entity of a real environment. |
| Scene Geometry | The digital representation of the object arrangement of a scene. |
| – Audio | A Data Type describing the spatial arrangement of the Visual Objects of a Scene. |
| – Audio-Visual | A Data Type describing the spatial arrangement of the Audio, Visual, and Audio-Visual Objects of a Scene. |
| – Visual | A Data Type describing the spatial arrangement of the Visual Objects of a Scene. |
| Speech | Digital representation of analogue speech sampled at a frequency between 8 kHz and 96 kHz with a number of bits/sample of 8, 16 or 24, and non-linear and linear quantisation or compressed. Data with characteristics of Speech may be synthetically produced. |
| Text | A sequence of characters represented according to [10]. |
| Virtual Space | A space generated and maintained by a computing platform that can be rendered. |
The Terms used in this standard whose first letter is capital and are not already included in Table 1 are defined in Table 62. To concentrate in one place all the Terms that are composed of a common name followed by other words (e.g., the word Data followed by one of the words Format, Type, or Semantics), the definition given to a Terms preceded by a dash “-” applies to a Term composed by that Term without the dash preceded by the Term that precedes it in the column without a dash.
Table 2 – MPAI-wide Terms and Definitions
| Term | Definition |
| Access | Static or slowly changing data that are required by an application such as domain knowledge data, data models, etc. |
| AI Framework (AIF) | The environment where AIWs are executed. |
| AI Model (AIM) | A data processing element receiving AIM-specific Inputs and producing AIM-specific Outputs according to according to its Function. An AIM may be an aggregation of AIMs. |
| AI Workflow (AIW) | A structured aggregation of AIMs implementing a Use Case receiving AIW-specific inputs and producing AIW-specific outputs according to the AIW Function. |
| Application Standard | An MPAI Standard designed to enable a particular application domain. |
| Channel | A connection between an output port of an AIM and an input port of an AIM. The term “connection” is also used as synonymous. |
| Communication | The infrastructure that implements message passing between AIMs. |
| Component | One of the 7 AIF elements: Access, Communication, Controller, Internal Storage, Global Storage, Store, and User Agent |
| Composite AIM | An AIM aggregating more than one AIM. |
| Component | One of the 7 AIF elements: Access, Communication, Controller, Internal Storage, Global Storage, Store, and User Agent |
| Conformance | The attribute of an Implementation of being a correct technical Implementation of a Technical Specification. |
| – Testing | The normative document specifying the Means to Test the Conformance of an Implementation. |
| – Testing Means | Procedures, tools, data sets and/or data set characteristics to Test the Conformance of an Implementation. |
| Connection | A channel connecting an output port of an AIM and an input port of an AIM. |
| Controller | A Component that manages and controls the AIMs in the AIF, so that they execute in the correct order and at the time when they are needed |
| Data | Information in digital form. |
| – Format | The standard digital representation of Data. |
| – Type | An instance of Data with a specific Data Format. |
| – Semantics | The meaning of Data. |
| Descriptor | Coded representation of a text, audio, speech, or visual feature. |
| Digital Representation | Data corresponding to and representing a physical entity. |
| Ecosystem | The ensemble of actors making it possible for a User to execute an application composed of an AIF, one or more AIWs, each with one or more AIMs potentially sourced from independent implementers. |
| Explainability | The ability to trace the output of an Implementation back to the inputs that have produced it. |
| Fairness | The attribute of an Implementation whose extent of applicability can be assessed by making the training set and/or network open to testing for bias and unanticipated results. |
| Function | The operations effected by an AIW or an AIM on input data. |
| Global Storage | A Component to store data shared by AIMs. |
| AIM/AIW Storage | A Component to store data of the individual AIMs. |
| Identifier | A name that uniquely identifies an Implementation. |
| Implementation | 1. An embodiment of the MPAI-AIF Technical Specification, or
2. An AIW or AIM of a particular Level (1-2-3) conforming with a Use Case of an MPAI Application Standard. |
| Implementer | A legal entity implementing MPAI Technical Specifications. |
| ImplementerID (IID) | A unique name assigned by the ImplementerID Registration Authority to an Implementer. |
| ImplementerID Registration Authority (IIDRA) | The entity appointed by MPAI to assign ImplementerID’s to Implementers. |
| Instance ID | Instance of a class of Objects and the Group of Objects the Instance belongs to. |
| Interoperability | The ability to functionally replace an AIM with another AIW having the same Interoperability Level |
| – Level | The attribute of an AIW and its AIMs to be executable in an AIF Implementation and to:
1. Be proprietary (Level 1) 2. Pass the Conformance Testing (Level 2) of an Application Standard 3. Pass the Performance Testing (Level 3) of an Application Standard. |
| Knowledge Base | Structured and/or unstructured information made accessible to AIMs via MPAI-specified interfaces |
| Message | A sequence of Records transported by Communication through Channels. |
| Normativity | The set of attributes of a technology or a set of technologies specified by the applicable parts of an MPAI standard. |
| Performance | The attribute of an Implementation of being Reliable, Robust, Fair and Replicable. |
| – Assessment | The normative document specifying the Means to Assess the Grade of Performance of an Implementation. |
| – Assessment Means | Procedures, tools, data sets and/or data set characteristics to Assess the Performance of an Implementation. |
| – Assessor | An entity Assessing the Performance of an Implementation. |
| Profile | A particular subset of the technologies used in MPAI-AIF or an AIW of an Application Standard and, where applicable, the classes, other subsets, options and parameters relevant to that subset. |
| Record | A data structure with a specified structure |
| Reference Model | The AIMs and theirs Connections in an AIW. |
| Reference Software | A technically correct software implementation of a Technical Specification containing source code, or source and compiled code. |
| Reliability | The attribute of an Implementation that performs as specified by the Application Standard, profile, and version the Implementation refers to, e.g., within the application scope, stated limitations, and for the period of time specified by the Implementer. |
| Replicability | The attribute of an Implementation whose Performance, as Assessed by a Performance Assessor, can be replicated, within an agreed level, by another Performance Assessor. |
| Robustness | The attribute of an Implementation that copes with data outside of the stated application scope with an estimated degree of confidence. |
| Scope | The domain of applicability of an MPAI Application Standard |
| Service Provider | An entrepreneur who offers an Implementation as a service (e.g., a recommendation service) to Users. |
| Standard | A set of Technical Specification, Reference Software, Conformance Testing, Performance Assessment, and Technical Report of an MPAI application Standard. |
| Technical Specification | (Framework) the normative specification of the AIF.
(Application) the normative specification of the set of AIWs belonging to an application domain along with the AIMs required to Implement the AIWs that includes: 1. The formats of the Input/Output data of the AIWs implementing the AIWs. 2. The Connections of the AIMs of the AIW. 3. The formats of the Input/Output data of the AIMs belonging to the AIW. |
| Testing Laboratory | A laboratory accredited to Assess the Grade of Performance of Implementations. |
| Time Base | The protocol specifying how Components can access timing information |
| Topology | The set of AIM Connections of an AIW. |
| Use Case | A particular instance of the Application domain target of an Application Standard. |
| User | A user of an Implementation. |
| User Agent | The Component interfacing the user with an AIF through the Controller |
| Version | A revision or extension of a Standard or of one of its elements. |
| Zero Trust | A cybersecurity model primarily focused on data and service protection that assumes no implicit trust. |
