The International Plain Language Federation initiated a project to create a plain language standard through the International Organization for Standardization (ISO). Plain language experts decided to do the standard through ISO for two reasons:

• the credibility of ISO, with a network of 174 national standards bodies and more than 22,500 standards
• the credibility of being developed with input and support from many plain language experts around the world

A plain language standard provides a clear understanding of what plain language is and how you can achieve it. Without a standard, there is no universally agreed-on principles for creating plain language documents or for determining whether something is plain.

This makes it difficult for people writing and designing documents to assess the quality of their processes and their documents. Having an international standard means that everyone can work from the same understanding.

The International Organization for Standardization (ISO) has published a plain language standard:
ISO 24495-1:2023  Plain language — Part 1: Governing principles and guidelines.