What does GRZ stand for?

Design Concepts, Chico, CA - Manufacturer code for watercraft hull identification number (USCG)

Galapagos Rift Zone - Marine science (MSC)

Granophyric Roof Zone - Geology

Graz - Austria - Airport symbol (OAG)

Greiz - German license plate city code

Guramalum - Language code (ETLW)