1     Definition 2     Functional Requirements 3     Syntax
4     Semantics 5    Conformance Testing 6     Performance Assessment

1      Definition

A Data Type conveying information about position, orientation, spatial relationships, and activation conditions within a defined reference frame and providing absolute, relative, semantic, regional, or constrained spatial targeting for multimodal interactions in MPAI‑OSD..

2      Functional Requirements

Cue Identification

Must include a cue type (CueType) identifying the nature of the cue: absolute, relative, keyword‑based, region‑based, or range‑constrained.

Reference Frame Support

Must support multiple coordinate frames: World, Entity, Device, Object

Location Specification

Must support: Absolute positioning (Position, Orientation, LocationRef), Relative positioning (RelativeExpression), Semantic expressions (Keyword)

Region Definition

Must allow region‑based spatial specification using Region.json: Right Parallelepiped, Sphere, or Cylinder.

Range Constraints

Must allow optional range refinement using RangeConstraint.json: Distance bounds, Directional offsets, Semantic policies, Inside/outside conditions

Triggering Conditions

A Spatial Cue must be activatable through a Trigger, which may be: A TimeEvent (at / after a moment in time), A SpatialEvent (enter/exit a region, inside/outside, distance thresholds), A StateEvent (logical or contextual condition reached)

Trigger must be represented as a JSON object with: Type: event category, event‑specific properties (TimeEvent, SpatialEvent, StateEvent)

Confidence Level

A numeric confidence (0–1) indicating cue reliability.

Metadata

Must include descriptive metadata (DescrMetadata) and traceability (Trace).

Validation Rules

  • Required fields depend on CueType.
  • Trigger must validate as a structured predicate.
  • RelativeExpression and Keyword must follow enums.
  • Region and RangeConstraint must validate against their schemas.

Extensibility

Must allow additional shapes, coordinate types, trigger types, and keywords in future versions..

3      Syntax

https://schemas.mpai.community/OSD/V1.5/data/SpatialCue.json

4      Semantics

Table 1 provides the semantics of the components of Spatial Cue.

Table 1 – Semantics of the Spatial Cue

Label Description
Header Spatial Cue Header – Standard “OSD-SCU-V”.
MInstanceID ID of Virtual Space the cue refers to.
SpatialCueID Unique identifier of the cue instance.
SpatialCueData Contextual and structural components of the cue.
CoordinateType Coordinate system used (Cartesian, Spherical, Geodesic, Toroidal).
ReferenceFrame Spatial frame: World, Entity, Device, Object.
CueType Type of cue (absolute, relative, keyword, region, range).
MediaType Rendering modality: Speech, Audio, Visual, etc.
Time Time interval or instant when cue is active.
Trigger Structured event predicate that activates the cue.
Type Category of trigger (TimeEvent, SpatialEvent, StateEvent).
TimeEvent Activates based on explicit time moments or delays.
SpatialEvent Activates based on entering/exiting a region, distance thresholds, or inside/outside tests.
StateEvent Activates when a named condition or external state becomes true.
Position Absolute 3D position.
Orientation Absolute orientation.
LocationRef Reference to external Location.
RelativeExpression Relative direction expression (right, front, up…).
Keyword Semantic spatial term (near, inside…).
Region Geometric region (Right Parallelepiped, Sphere, Cylinder).
RangeConstraint Numeric/directional constraint refinement.
Confidence Confidence score (0–1).
Trace AIF trace information.
DescrMetadata Descriptive metadata.

5     Conformance Testing

A Data instance Conforms with V1.5 Spatial Cue(OSD-SCU) if:

  1. Its JSON Object validates against its JSON Schema.
  2. Any included  JSON Object validates against its JSON Schema.
  3. All Data in the JSON Object:
    1. Have the specified Data Types.
    2. Conform with the Qualifiers signaled in their JSON Schemas.

6     Performance Assessment