Standards are regularly revised and updated. One version of a standard remains in place until a newer version is released. When working on a project, you should refer to the version of a standard that is currently adopted.

Most publishers will say on their website when new versions of a standard were released. It's a good idea to make sure the standard you're looking hasn't been replaced.

For example, a new draft of ICC/ANSI A117.1, Accessible and Usable Buildings and Facilities, was open for comment in summer 2023. Until that draft is formally adopted, the current standard remains ICC A117.1-2017, Standard for Accessible and Usable Buildings and Facilities.

There were earlier versions of this standard as well. Titles and even organization acronyms have changed over the decades.