Terms beginning with a capital letter have the meaning defined in Table 1. The Terms used in this standard whose first letter is capital and are not already included in Table 1 are defined in Table 2.
Terms beginning with a small letter have the meaning commonly defined for the context in which they are used. For instance, Table 1 defines Object and Scene but does not define object and scene.
A dash “-” preceding a Term in in Table 1 means the following depending on whether the font is:
- Normal, the Term in the table without a dash and preceding the one with a dash should be placed before that Term.
- Italic, the Term in the table without a dash and preceding the one with a dash should be placed after that Term.
All MPAI Terms are accessible online.
Table 1 –Terms and Definitions
| Term | Definition |
| Actuator | A mechanism for modulating an experience in a real or virtual world. |
| AI Module | (AIM) A 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. |
| 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. |
| Avatar | A rendered animated 3D digital object representing a real or fictitious person. |
| Biometric Data | Biological data collected from participants or performers including heart rate, electromyographic (EMG) data, skin conductance, etc. |
| Cognitive State | An estimation of the internal status of a human or avatar or a group thereof reflecting their understanding of the Environment, such as: – For a person: “Confused”, “Confident” and “Assured”. – For a group: “my team is going to lose”, or “we are winning”. |
| Controller | A manual control interface for participants, performers, or operators. |
| Cue Point | The position in the Script at any given time that an AIM, operator, or performer uses to generate Action according to the Script. |
| Data | Information in digital form. |
| – Format | The syntax and semantics of Data. |
| Descriptor | Digital representation of a Feature. |
| – Action | Components of the description that are used to create the complete user experience – in both Real and Virtual Environments – in accordance with the script. This includes all aspects of the experience including the performers and objects’ position, orientation, gesture, costume, audio, video, etc. |
| – Extraction | The process that extracts Descriptors from Data. |
| – Generation | The process that generates attributes to be applied to a scene or object according to the Script. |
| – Interpretation | The process that assigns a meaning to Descriptors. |
| – Scene | A Descriptor used to describe a Scene in the Real or Virtual Environment. |
| Dome display | Wrap-around immersive display surrounding an audience, using a projection screen or LED panels, technically known as Spatial Augmented Reality. |
| Emotion | An estimation of the internal status of a human or avatar or a group thereof resulting from their interaction with the Environment, such as:
For a person, “Victorious”, “Fearful” and “Angry”. For a group: “Victorious”, “Fearful” and “Disappointed” |
| Environment | A portion of a real or a virtual world. |
| Extended Reality (XR) | Any combination of Augmented Reality (AR), Virtual Reality (VR) and Mixed Reality (MR). |
| Feature | An attribute of an object or a scene in a Real or Virtual Environment. |
| Gesture | A Data Type representing the movement of the body or part of it, such as the head, arm, hand, and finger, often a complement to a vocal utterance. |
| Interpreted Operator Controls | The assignment of meaning of data from control surfaces. |
| LiDAR Data | Data provided by LiDAR, an active time-of-flight sensor operating in the µm range – ultraviolet, visible, or near infrared light (900 to 1550 nm). |
| MoCap | Data capturing the movement of people or objects. |
| Participant | A human in a Real or Virtual Environment (Venue). |
| – Data | Data provided by or collected from Participants. |
| – Data Management | The set of legal, ethical, marketing, maintenance, etc. rules guiding the acquisition, retention, and processing of Data related to and provided by Participants. |
| – Descriptors | Data that describe Participants behaviour in the Rean Environment (including visual, audio, and choice components) and in the Virtual Environment (including Avatar spatial position, motion, and Audio components). |
| – Engagement Engine | Algorithms to engage participants during or after the event allowing social interaction, commerce, and other engagement modalities. |
| – Status | The ensemble of information, expressed by Emotion, Cognitive State and Social Attitude, derived from observing the collective behaviour of participants in a Real and on-line Environment, or in a Virtual Environment. |
| Performer | A live actor performing on the Real Environment stage or represented by an avatar in the Virtual Environment. |
| Script | A collection of descriptors that the director/producer selects for execution at runtime controlling the action/experience in both Real and Virtual Worlds. |
| Sensor | A mechanism capturing data from a real or virtual Environment. |
| Show Control | Externally generated commands from an operator or show control system that pertain to desired Actions in the Real or Virtual Environment |
| Social Attitude | An element of the internal status related to the way a human or avatar intends to position vis-à-vis the Environment, e.g.: For person: “Confrontational”, “Collaborative” and “Aggressive”. For groups: “Confrontational”, “Collaborative” and “Aggressive” |
| Use Case | A particular instance of the Application domain target of an MPAI Application Standard. |
| Real Venue Specification | The specification of the physical venue and all experiential technologies including lighting (fixture type and placement, DMX profile), FX, video displays, acoustics, sound reinforcement, stage props, preset cues and participant interactive devices. |
| Virtual Venue Specification | The specification of the virtual venue and all available experiential systems for the delivery of audio, video, 3D environments, preset cues, and participant interactive devices. |
| Volumetric Visual Data | A set of samples representing the value of visual 3D data represented as textured meshes, points clouds, or UV + depth. |
| XR Venue | A combination of Real or Virtual Environments addressed by MPAI-XRV Use Cases. |
Table 2 – MPAI-wide definitions
The Terms used in this standard whose first letter is capital and are not already included in Table 1 are defined in Table 2.
Note: 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.
| 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 MPAI-appointed entity assigning 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. |
