ABSTRACT
Provide literal guidelines on products and in public spaces to indicate the desired path that a person or machine should follow to remain safe, or to indicate a boundary line that people should not cross to avoid harm. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315098128/b099026f-9515-46ed-a3c2-be7b65836945/content/ufig88_1.jpg" xmlns:xlink="https://www.w3.org/1999/xlink"/>
