Hierarchy classification:

1. top of the aat hierarchies
2. Brand Names Facet
3. Brand Names (hierarchy name)
4. brand name materials

Anotations

Scope note:

Commercially produced, British acrylic plastic consisting essentially of polymerized methyl methacrylate. Polymethyl methacrylate was discovered in the early 1930s by British chemists at Imperial Chemical Industries in England and trademarked the name Perspex.