2010 ADA Standards for Accessible Design Pocket Guide
407.2.3.1 Floor Designation.
Floor designations complying with 703.2 and 703.4.1 shall be provided on both jambs of elevator hoistway entrances. Floor designations shall be provided in both tactile characters and braille. Tactile characters shall be 2 inches (51 mm) high minimum. A tactile star shall be provided on both jambs at the main entry level. [S.H. 4.10.5]