What does the RVR value represent on certain straight in IAP charts?

The RVR, or Runway Visual Range, specifically refers to the horizontal distance that a pilot can see down the runway from the runway threshold. It is a crucial measurement in instrument approaches, especially during low visibility conditions, as it helps determine whether the visibility is acceptable for landing. The RVR value indicates how far a pilot can see along the runway, providing essential information for decision-making during the landing phase.

In contrast, other terms like "distance from the touchdown point" or "slant range visibility" may pertain to different measurements that do not specifically indicate horizontal visibility along the runway. Furthermore, the option relating to maximum distance for crew visibility using night goggles is unrelated to standard RVR measures, which focus on runway visibility for landing operations under instrument flight rules.