What do passing calls in property surveying indicate?

Passing calls in property surveying indicate uncertain endpoints. This phrase refers to the instructions or dimensions in a property description that are not definitive and may lack clear or fixed markers. When a surveyor encounters passing calls, it means that the endpoints of certain calls, which describe the boundaries or corners of a property, might be ambiguous or imprecise. This brings about the understanding that additional survey work may be needed to clarify or confirm the exact location of these boundaries.

The other choices relate to different surveying concepts. Fixed control lines are established points used as reference in surveying, while starting point markers denote where a survey begins, and coordinates for survey boundaries provide exact locations rather than implying uncertainty. Therefore, the nature of passing calls is specifically tied to the ambiguity of their endpoints in a property description.