Not Found Mark was searched for and not found, however no evidence exists to indicate that it was destroyed. U Uncertain Mark was found, however it was in an unstable condition or there was evidence that it had been disturbed or moved to another location. Status will remain uncertain until verified by survey. Coordinates are to be used with caution. S Subsidence Area Mark is located in an area identified by the Mines Subsidence Board as being subject to movement.
Coordinates are to be used with caution.
F Found Intact Mark was found in good condition. The following are extracts from ICSM SP1 . Order Order is a function of the Class of a survey, the conformity of the new survey data with an existing network coordinate set and the precision of any transformation process required to convert results from one datum to another. Stations in horizontal control surveys are assigned an Order commensurate with the Class of the survey and the conformity of the survey data with the existing coordinate set. It is accepted that some heighting techniques such as differential levelling propagate errors in proportion to the square root of the distance.