number refers to a reference base picture that is marked as "used for long-term reference" (and as "reference base picture") when the memory_management_base_control_operationis processed by the decoding process. When the pic_marking() syntax structure contains a memory_management_control_operation equal to memory_management_base_control_operation shall not be equal to 1 or 2. Table G-3 - Memory management base control operation (memory_management_base_control_operation)values mnemory_management_base_control_operation Memory Management Base Control Operation End memory_management_base_control_operat syntax element loop Mark a short-term reference base picture as "unused for reference" Mark a long-term reference base picture as "unused for reference" difference _of_base_pic_nums_minus] is used (with mnemory_management_base_control_operatione equal to 1) to mark short-term reference base picture as "unused for reference". When the associated memory_management_base_control_operation is processed by the decoding process, the resulting picture number Rec. ITU-T H.264 (01/2012) derived from difference_of_base_pic_nums_minus1 shall be a picture number assigned to one of the reference pictures marked as "used for short-term reference" and as "reference base picture". The resulting picture number is constrained as follows: If field_pic_flag is equal to 0, the resulting picture number shall be one of the set of picture numbers assigned to reference frames or complementary reference field pairs marked as "reference base picture". NOTE 2 - When field_pic_flag is equal to 0, the resulting picture number must be a picture number assigned to a complementary reference field pair in which both fields are marked as "used for short-term reference" and "reference base picture" or a reference frame in which both fields are marked as "used for short-term reference" and "reference base picture". Otherwise (field_pic_flag is equal to 1), the resulting picture number shall be one of the set of picture numbers assigned to reference fields 