<http://schema.org/description>
"&lt;p&gt;ANSI and ISO standards include many different parameters for measuring surface finish. While these parameters are useful in many applications to ensure or enhance functionality, Ra, or average roughness, is by far the most common measure of surface finish. It is included in most specs, and it is both a good starting point and a basic benchmark of process consistency.&lt;/p&gt;"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.mmsonline.com/columns/skidded-probes-for-roughness-measurement>