||"change_over_time_in_X" means change in a quantity X over a time-interval, which should be defined by the bounds of the time coordinate. Sea water salinity is the salt content of sea water, often on the Practical Salinity Scale of 1978. However, the unqualified term &apos;salinity&apos; is generic and does not necessarily imply any particular method of calculation. The units of salinity are dimensionless and the units attribute should normally be given as 1e-3 or 0.001 i.e. parts per thousand. There are standard names for the more precisely defined salinity quantities: sea_water_knudsen_salinity, S_K (used for salinity observations between 1901 and 1966), sea_water_cox_salinity, S_C (used for salinity observations between 1967 and 1977), sea_water_practical_salinity, S_P (used for salinity observations from 1978 to the present day), sea_water_absolute_salinity, S_A, sea_water_preformed_salinity, S_*, and sea_water_reference_salinity. Practical Salinity is reported on the Practical Salinity Scale of 1978 (PSS-78), and is usually based on the electrical conductivity of sea water in observations since the 1960s. Conversion of data between the observed scales follows: S_P = (S_K - 0.03) * (1.80655 / 1.805) and S_P = S_C, however the accuracy of the latter is dependent on whether chlorinity or conductivity was used to determine the S_C value, with this inconsistency driving the development of PSS-78. The more precise standard names should be used where appropriate for both modelled and observed salinities. In particular, the use of sea_water_salinity to describe salinity observations made from 1978 onwards is now deprecated in favor of the term sea_water_practical_salinity which is the salinity quantity stored by national data centers for post-1978 observations. The only exception to this is where the observed salinities are definitely known not to be recorded on the Practical Salinity Scale. The unit "parts per thousand" was used for sea_water_knudsen_salinity and sea_water_cox_salinity.