The World Wide Web Consortium publishes first public draft of SHACL 1.2 Node Expressions
A new draft specification explains how computers can more clearly describe and check the structure of data on the web, helping systems understand whether information is complete, valid, and consistent.
The World Wide Web Consortium (W3C) has published a First Public Working Draft of SHACL 1.2 Node Expressions, a technical document developed by the Data Shapes Working Group. While the subject is highly technical, the goal behind it is relatively simple: to make it easier for computers to check whether data is structured in the right way.
At the centre of the document is something called SHACL, short for Shapes Constraint Language. SHACL is a way of describing rules for data. These rules, known as ‘shapes,’ define what data should look like. For example, a shape might say that a dataset describing people must include a name, or that an address must contain both a street and a city.
Node Expressions are a new building block within SHACL. In simple terms, they provide a more flexible way to describe what kinds of data items are allowed or expected at a certain point in a dataset. Instead of listing rules one by one, node expressions let data designers combine conditions, reuse definitions, and express constraints more clearly and compactly.
This matters because large amounts of data are shared between systems every day, from public sector databases to scientific research and digital services. If data does not follow agreed-upon structures, systems can misinterpret it, leading to errors, incomplete results, or failed integrations. SHACL helps prevent this by allowing automatic checks before data is used or shared.
The draft is part of the broader SHACL 1.2 family of specifications, which aim to improve how data constraints are written and processed. The ‘first public working draft’ status means the document is an early version shared openly so that developers, researchers, and other stakeholders can review it and provide feedback before it is finalised.
Importantly, this draft does not introduce new rules for end users or organisations. Instead, it is guidance for tool builders and data professionals who design systems that rely on structured data, particularly in environments where data needs to be reliable, reusable, and machine-readable.
Further background and context on SHACL 1.2 and how node expressions fit into the overall framework are available through the W3C’s SHACL 1.2 Overview.
