Gr 1 : An ambiguous symbol, traditionally used in English both for the grain and the gross. It has also been used, very improperly, for the gram (g). In the metric world, gr is often the symbol for the grad or grade (next entry)
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}