A witness post is an auxiliary marker such as a plastic or metal post that has been driven into the ground near the ["station"] in order to make it easier to find. A "Carsonite" witness post is a plastic post made by one well-known manufacturer. Sometimes a witness post will bear a small sign indicating that a survey marker is nearby.

Some ["datasheet"]s include the distance and ["azimuth"] from the station to the witness post and some do not.