ODM2 Variable Name Controlled Vocabulary ODM2 Working Group A vocabulary for describing the name of Variables. Sand USDA particle size distribution category. 0.5 to 2 mm diameter fine earth particles. NRCS USDA See description at http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ref/?cid=nrcs142p2_054253