The following uses shall be permitted as a matter of right in an SP District:
An artist studio shall be permitted as a matter of right in an SP District, subject to the following criteria:
General office use, including chancery, shall be permitted in an SP District as a replacement for office use for international organization, non-profit organization, labor union, architect, dentist, doctor, engineer, lawyer, or similar professional person existing and approved by the Board of Zoning Adjustment or the Zoning Commission or authorized by a validly issued certificate of occupancy prior to January 29, 1999.
D.C. Mun. Regs. tit. 11, r. 11-501