These codes are called Property Use Codes and are abbreviated PU Code.
Property is classified as either real or personal.
Real property is defined as land, improvements, mines or quarries, minerals in place, and standing timber. Personal property is defined as all property that is not real, such as business inventory, furniture and fixtures, machinery and equipment, vehicles, supplies, etc. Only personal property that is used to produce an income is taxable. Personal property is defined as tangible and intangible. If you cannot perceive the property itself, it is intangible.