Test points
Test points are the basic survey items, that are used to capture cathodic protection data. Test points has fixed set of properties such as name, type, latitude and longitude and etc.
In addition to properties, test points contain "Reading items" (referred as Readings). Reading items examples are test leads, coupons, shunts, risers etc. Single test point can have unlimited number of readings.

Readings also have their own properties, and they can also contain voltage and current fields, where field data can be recorded. This layered structure allows to create complex test points that could be often encountered in the field.