California Code, Health and Safety Code - HSC § 51401

(a) “Mortgage loan” means any residential mortgage loan or multifamily rental housing loan.

(b) “Multifamily rental housing” means any existing structure of more than four dwelling units or any work or undertaking of more than four units of new construction, improvement, or rehabilitation for the provision of housing.

(c) “Multifamily rental housing loan” means a mortgage loan secured by a mortgage on multifamily rental housing.

(d) “Residence” means any existing structure of one to four dwelling units or any work or undertaking of one to four dwelling units of new construction, improvement, or rehabilitation for the provision of housing.

(e) “Residential mortgage loan” means a mortgage loan secured by a mortgage on a residence.

(f) “Taxable securities” means securities bearing interest that is otherwise taxable under the personal income tax provisions of federal tax law and which are issued to finance the purchase or making of mortgage loans pursuant to this chapter.