Definition
Functional Requirements
Syntax
Semantics
Conformance Testing
Performance Assessment
Definition
CXE Directive (PGM‑CED) is a Directive issued by A‑User Control to Context Enhancement. It specifies what A‑User Control needs Context Enhancement to deliver: enhanced descriptions of the audio scene, of the visual scene, or a first‑pass User Entity State. It may also request, about referenced entities, baseline semantic information elements such as object classification, salience, occlusion, depth, proximity, or attention, and it may install watch requests asking Context Enhancement to report when a spatial‑relational condition over referenced entities holds, for example when a User reaches a referenced object. It identifies the subjects of enhancement by reference, an M‑Location, Objects, or Users, each given inline or by identifier, and it sets the point of view and the execution controls. A‑User Control does not specify the signal‑processing method by which Context Enhancement computes these elements; it names what it needs, and Context Enhancement decides how. Context Enhancement performs its own interaction‑history operations as needed; A‑User Control does not instruct them.
Functional Requirements
- Session and Directive Identification: The directive shall include a SessionID, a unique CXEDirectiveID, and a CXEDirectiveTime timestamp to ensure traceability and correlation with execution status.
- Environment Identification: The directive shall include identifiers for the M‑Instance (MInstance) and U‑Environment (UEnvironment) in which the directive applies.
- Exchange Phase: The directive shall indicate whether it opens a new exchange or continues an existing one, and on a continuation shall reference the CXE Status (CXEStatusID) it follows.
- Deliverable Specification: The directive shall specify, in Deliver, the deliverable type or types required: Enhanced Audio Scene Descriptors, Enhanced Visual Scene Descriptors, or User Entity State.
- Subject Identification: The directive may identify the subjects of enhancement by reference, an M‑Location, Objects, or Users, each provided inline or by identifier.
- Semantic Property Requests: The directive may request, in Properties, baseline semantic information elements about referenced entities, drawn from a defined vocabulary.
- Watch Requests: The directive may install, in Watches, requests to report when a spatial‑relational predicate over referenced entities holds, each identified by a WatchID.
- Perceptual Framing: The directive may include a PointOfView, a Spatial Attitude defining the perspective for enhancement.
- Execution Control: The directive may include a Duration, a PriorityLevel, and a Deadline.
- Data Exchange Metadata: The directive shall include DataXMData to provide standardised metadata supporting interoperability, traceability, and data exchange control.
- Descriptive Metadata: The directive may include DescrMetadata to carry additional human‑readable context.
Syntax
https://schemas.mpai.community/PGM1/V1.0/data/CXEDirective.json
Semantics
| Label | Description |
|---|---|
| Header | CXE Directive header identifier. Value: “PGM-CED-V1.0”. |
| MInstance | Identifier of the M-Instance in which the directive applies. |
| UEnvironment | Identifier of the U-Environment associated with the directive. |
| CXEDirectiveID | Unique identifier for this CXE Directive instance. |
| CXEDirectiveTime | Timestamp indicating when the directive was produced, compliant with MPAI-OSD V1.5. |
| SessionID | Identifier of the A-User session to which the directive belongs. |
| Exchange | Container indicating the directive’s place in the interaction. |
| – Phase | Whether the directive opens a new exchange or continues one: new | continuation. |
| – CXEStatusID | Identifier of the CXE Status this directive follows, present on a continuation. |
| Subject | Container identifying the subjects of enhancement by reference. |
| – MLocation | One or more M-Locations of interest, each an OSD Location or its identifier. |
| – Objects | One or more Objects of interest, each an Audio or Visual Object or its identifier. |
| – Users | One or more Users of interest, by identifier. |
| Deliver | The deliverable type or types required: EnhancedAudioSceneDescriptors | EnhancedVisualSceneDescriptors | UserEntityState. |
| Properties | Requested baseline semantic information elements about referenced entities. |
| – Element | The requested element: ObjectClassification | Salience | InteractionPotential | Occlusion | Depth | ProximityClass | Correspondence | IsUser | AttentionTarget | UserAffect | UserEngagement. |
| – EntityIDs | Identifiers of the entities the element concerns. |
| Watches | Requests to report when a spatial-relational condition over referenced entities holds. |
| – WatchID | Identifier of this watch, used to correlate the reported event. |
| – Predicate | The condition watched: enters | leaves | reaches | contacts | approaches | proximity_threshold. |
| – Entities | Identifiers of the entities the predicate relates. |
| – Reference | A reference entity or region the predicate is evaluated against, an OSD Location or its identifier. |
| – Threshold | Numeric threshold for predicates that require one, such as proximity. |
| PointOfView | Spatial Attitude defining the perspective for enhancement, compliant with MPAI-OSD V1.5. |
| Control | Container of execution controls. |
| – Duration | Duration of the processing window in milliseconds. May be zero for a snapshot. |
| – PriorityLevel | Execution urgency: low | normal | high. |
| – Deadline | Time by which the enhancement is required, compliant with MPAI-OSD V1.5. |
| DataXMData | Data Exchange Metadata compliant with MPAI-PTF V1.0. |
| DescrMetadata | Optional descriptive metadata providing additional human-readable context. |
Conformance Testing
Not part of this specification.
Performance Assessment
Not part of this specification.
