Namespace Registration : eXtendable Scene Graph

Namespace ID:
XSG
Document version:
1.05
Date last modified:
3rd December 2025
Registrant:
Name: Stephen J.H. Williams
E-mail: steve@advance-software.com
Affiliation: Managing Director, Advance Software Limited.
Address: Unit 123, Kingsway North, Gateshead, United Kingdom. NE11 0JH.
Web URL: http://advance-software.com

The requesting entity is a corporation that has developed the proposed 3D web standard.

Management of the XSG 3D web standard may move to a separate standards development organization, “XSG Consortium” in due course, should there be sufficient demand for this transition to take place.
For the time being, Advance Software will manage the file format & standardization process.

Purpose

The XSG (eXtendable Scene Graph) format is an XML-derived file format used to design and deliver 3D website (aka metaverse) content.
XSG can be considered a 3D/virtual reality equivalent of HTML. XSG is optionally binary encoded using FastInfoset encoding.

This URN is requested so we can explicitly and unambiguously specify a FastInfoset stream as being XSG-encoded using an XSG external dictionary.

XSG FastInfoset binary-encoded values are little-endian.

Overview

XSG defines geometry, surface detail (textures), behaviour (scripting), audio, video and other characteristics associated with 3D website content.
It is defined such that each XSG-compatible solution exhibits the same behaviour as that delivered by our Infinity 3D web browser reference implementation and associated tools and technology.

At this time, Advance Software is responsible for:

Information concerning XSG usage can be found on our website: http://advance-software.com/xsg

URN Syntax

The optional namespace-specific string follows the requested 'XSG' URN identifier. This string begins with a major, optional .minor version number.
This can optionally be followed by a comma-separated list of third-party extensions in the same format required to fully interpret the stream.

xsg:a[.b][,ext:a[.b]]n

Where:

Assignment

Evolution of the XSG format is the sole responsibility of Advance Software Limited acting as the proposed XSG Consortium at this time.
Legal morph to an international non-profit standards organization with multiple members will follow, subject to interest & funding to cover administrative costs.

Our launch event on 3rd December 2025 will ratify the XSG 1.0 specification by the XSG Consortium if there are no objections by members of the consortium. Non-members are welcome to voice opinions but do not have blocking votes.

In order to ensure extensions can be uniquely identified, each extension should be registered with the XSG Consortium.
Extension registration is conducted over email by making an enquiry to xsg@advance-software.com.
Only extensions which provide enough information to determine they are genuine (rather than namespace opportunists) will be accepted.

The base format should be used directly in most cases to prevent format divergence, version management difficulties and unnecessary complexity.

XSG Syntax

A working definition of the XSG format can be found at http://advance-software.com/xsg

Security and Privacy

Extension documentation can be open or secure/private at the extension developer’s request.

The core XSG format is an open standard for data interchange. Security and privacy of 3D web content occurs at the transport and application layers and/or within third-party extensions.

XSG 3D website content can be securely manipulated from untrusted third-party WebAssembly code using the XSG 3D web document object model (DOM).
Details here: https://advance-software.com/develop

Interoperability

XSG is a unique and persistent format. Each extension or format version revision, once defined, must never be re-used for another purpose or interpreted in some other way in order to prevent standards divergence.

Resolution

General

XSG-encoded streams are created and decoded by software tools including navigators (3D web browsers) and format manipulation tools (e.g. importers, exporters, converters) that understand the format.
The Infinity 3D web browser delivers a reference implementation of the intended interpretation of the format.
Over time a formal definition of the intended behaviour will be delivered. XSG streams can also be hand-edited in text/xml format.
text/xml format XSG files can be converted to fi/urn:xsg binary streams and vice versa.

Locating the appropriate resolver

Extension developers will deliver plugins, tools and scripts designed to interpret and deliver whatever functionality is exposed by their extension.
A working list of known relevant products will be maintained by the registrant (with the exception of any requested to be private).
The public list will be made available to third parties so they may load and interact with content containing third-party extended content.

XSG-compatible browsers will include the ability to identify whether a file contains extensions and will provide a means of accepting or rejecting that additional functionality.

An XSG-compatible browser should deliver all standard XSG functionality found within our reference implementation.

Reference Implementation

Documentation

Infinity User’s Manual: http://advance-software.com/products/browser

Browser and Tools

Web URLs:

Revision Information

This registration is based on XML standard version 1.0, amended to 1.01 (our proposal) which is 1.0 with the addition of:

  1. </> which means close current element.
  2. Quotes around element attribute values are optional where the value does not contain whitespace.
XSG 1.0 fastinfoset external dictionary is here.

XSG 1.0 URN is xsg_1

XSG Consortium Membership same rates as W3C equivalent.

Membership fees accepted this way for now.

http://advance-software.com/donate
http://advance-software.com/donate/uk