What must be permanently marked on a concrete marker used in surveying?

A concrete marker used in surveying is intended to serve as a long-lasting reference point for the location it marks. It is crucial for this marker to include information that identifies the exact location or purpose of the survey point. By marking the permanent survey point, surveyors ensure that future users can easily understand what the marker signifies and maintain accurate references for any surveying work conducted in the area.

The inclusion of the permanent survey point directly assists in establishing boundaries, locating property lines, and conducting any follow-up surveys. This is essential for maintaining the integrity and reliability of survey data over time. Therefore, marking the permanent survey point is vital to the marker's function and utility in professional surveying practice.

Other choices, while they may contain useful information, do not fulfill the primary purpose of the marker in the same way as indicating the permanent survey point. Address, installation date, and materials might provide context, but they are secondary to the primary role of ensuring the marker defines and identifies the survey location clearly and effectively.