As used in this chapter, unless the context requires a different meaning: “Commercial real estate” means any real estate other than (i) real estate containing one to four residential units or (ii) real estate classified for assessment purposes under the provisions of Article 4 (§ 58.1-3230 et seq.) of Chapter 32 of Title 58.1. Commercial real estate does not include single-family residential units, including condominiums, townhouses, apartments, or homes in a subdivision when leased on a unit-by-unit basis even though these units may be part of a larger building or parcel of real estate containing more than four residential units. “Principal broker” means the same as that term is defined in regulations promulgated by the Real Estate Board.