What subjects do the call letters cover?
Subclass G Geography (General).
Subclass GA Mathematical geography. Cartography.
Subclass GB Physical geography.
Subclass GC Oceanography.
Subclass GE Environmental sciences.
Subclass GF Human ecology. Anthropogeography.
Subclass GN Anthropology.
Subclass GR Folklore.
Subclass GT Manners and customs (General).
Subclass GV Recreation. Leisure.