7.4.5 TYPE 3 OPTIONAL DATA ELEMENTS

IODs and SOP Classes define Type 3 Data Elements that are optional Data Elements. Absence of a Type 3 element from a Data Set does not convey any significance and is not a protocol violation. Type 3 elements may also be encoded with zero length and no Value. The meaning of a zero length Type 3 Data Element shall be precisely the same as that element being absent from the Data Set.