irst-out mechanism for short-term reference pictures Adaptive reference base picture marking mode: A reference picture marking mode providing syntax elements to specify marking of reference base pictures as "unused for reference" memory_management_base_control_operations specifies a control operation to be applied to affect the marking of reference base pictures. Thememory_management_base_control_operation syntaxelement is followed by data necessary for the operation specified by the value of memory_management_base_control_operation. The values and control operations associated with memory_management_base_control_operation are specified in Table G-3. The memory_management_base_control_operationsyntax elements are processed by the decoding process in the order in which they appear, and the semantics constraints expressed for each memory_management_base_control_operation apply at the specific position in that order at which that individual memory_management_base_control_operation is processed. For interpretation of memory_management_base_control_operation, the terms reference picture and reference base picture are interpreted as follows: If the current picture is a frame, the term reference picture refers either to a reference frame or a complementary reference field pair and the term reference base picture refers either to a reference base frame or a complementary reference base field pair. Otherwise (the current picture is a field), the term reference picture refers either to a reference field or a field of a reference frame and the term reference base picture refers either to a reference base field or a field of a reference base frame. nemory_management_base_control_operation shall not be equal to 1 unless the specified reference base picture is marked as "used for short-term reference" (and as "reference base picture") when the nemory_management_base_control_operation, is processed by the decoding process. mnemory_management_base_control_operations shall not be equal to 2 unless the specified long-term picture 