This report, referred to as Deliverable 4.2 (D4.2), provides a key output of the XR4HUMAN project is rooted in the extensive findings of Deliverable 4.1, “Mapping Existing and Emerging Requirements for Interoperability in XR and Spatial Computing.” Its primary purpose is to equip stakeholder developers and creators with a comprehensive framework and actionable insights to foster an open, connected, and user-centric XR and spatial computing ecosystem.

The guideline is structured logically, first establishing a foundational understanding before diving into practical implementation.

It begins with an Introduction (Section 1) that sets the stage by defining the urgent need for interoperability in the rapidly evolving XR landscape, detailing the project’s context, and outlining the guide’s purpose and target audience.

Following this, the Background (Section 2) delves into the current state of the XR ecosystem, exploring both the immense opportunities presented by its technological diversity and the significant challenges posed by fragmentation and inconsistent data formats, all while highlighting critical emerging requirements such as cross-platform compatibility and universal accessibility.

Interoperability Defined (Section 3) then establishes a clear, multifaceted understanding of the concept, distinguishing between its crucial technical aspects—supported by standards such as ISO/IEC/IEEE 24765:2017—and equally vital legal/juridical and usage/ethical considerations.

Building on this, the Interoperability Guidelines: Bursting Bubbles (Section 4) offers high-level strategies for overcoming proprietary silos, advocating for open standards, modular design, and robust data portability as essential practices for developers and creators.

This leads into a deeper exploration of The 3 Pillars of Interoperability defined in deliverable 4.1 (Section 5), providing detailed best practices for technical API design and data formats for technical interoperability, outlining compliance strategies for legal/juridical interoperability, and emphasising human-centred design for usage/ethical interoperability.

The guideline further emphasises The Human Dimension (Section 6), drawing parallels from the successful core principles of the Web to guide the development of a human-centric Spatial Web, prioritising user agency, control, and accessibility by design.

It then addresses the Technological and Institutional Dimensions (Section 7), offering an overview of key standards development organisations (e.g., ETSI, ISO, W3C, IEEE, Khronos Group) and crucial XR standards (e.g., OpenXR, glTF), and encouraging active engagement with these bodies.

From Diverse Perspectives (Section 8) broadens the scope by examining interoperability through lenses such as infrastructure, technological convergence, digital-physical integration, governance, and accessibility, thereby ensuring a holistic understanding.

Finally, Challenges That Cause Interoperability Issues, Solutions, and Methods (Section 9) directly confront common obstacles such as vendor lock-in and data incompatibility, offering practical solutions and methodologies, including continuous testing and legal consultation.
The guideline concludes with a visual representation, a comprehensive Glossary, and a list of References to support its content. This structured approach aims to empower developers and creators to build a truly interconnected and equitable future for XR and Spatial Computing.

Human-driven Interoperability is what we should strive towards beyond XR4HUMAN