Schematron using XPath 2.0 Display Dictionary: If the Display_Direction class is in the label, it must be contained in a Display_Settings class. The attribute disp:horizontal_display_direction must be equal to one of the following values 'Left to Right', 'Right to Left'. The attribute disp:vertical_display_direction must be equal to one of the following values 'Bottom to Top', 'Top to Bottom'. Display Dictionary: In the pds:Local_Internal_Reference class, the value of the pds:local_identifier_reference must match the value of the pds:local_identifer of an Array class or sub-class within the File_Area. Display_Dictionary: In the pds:Local_Internal_Reference class, the value of the pds:local_reference_type must be 'display_settings_to_array'. The attribute disp:loop_flag must be equal to one of the following values 'true', 'false'. The attribute disp:loop_back_and_forth_flag must be equal to one of the following values 'true', 'false'. The attribute @unit must be equal to one of the following values 'frames/s'. The attribute disp:loop_back_and_forth_flag must be equal to one of the following values 'false', 'true'. The attribute @unit must be equal to one of the following values 'day', 'hr', 'julian day', 'microseconds', 'min', 'ms', 's', 'yr'. The attribute disp:loop_flag must be equal to one of the following values 'false', 'true'.