Final answer:
The question is about the specific airflow requirements for displacement over the line of demarcation between ante-buffer and buffer areas in cleanrooms, relevant to environmental engineering but the exact value is not provided in the question.
Step-by-step explanation:
The question pertains to the flow rate of air between different cleanroom areas, specifically the ante-buffer (ante-area) and the buffer area in a controlled environment. This is a topic that is typically associated with environmental engineering, specifically concerning airflow and contamination control in spaces like pharmaceutical compounding facilities.
The required displacement airflow over the line of demarcation from the buffer area to the ante area is not provided in the given context, as it is something that would be specified in guidelines such as USP 797 or other industry standards for cleanrooms and controlled environments. These standards dictate that there must be a specific airflow to prevent contamination from the less clean ante-area from entering the cleaner buffer area (where sterile products are prepared).