72 Pa. Stat. § 4749.3
The following words and phrases when used in this act shall have the meanings given to them in this section unless the context clearly indicates otherwise:
"Longtime owner-occupant." Any person who for at least ten continuous years has owned and has occupied the same dwelling place as a principal residence and domicile, or any person who for at least five years has owned and occupied the same dwelling as a principal residence and domicile if that person received assistance in the acquisition of the property as part of a government or nonprofit housing program.
"Principal residence." The dwelling place of a person, including the principal house and lot, and such lots as are used in connection therewith which contribute to its enjoyment, comfort and convenience. For purposes of this act, the term may also include a building with a maximum of one commercial establishment and a maximum of three residential units of which one residential unit must be the principal residence of the longtime owner-occupant.
72 P.S. § 4749.3