| scalar line integral of a magnetic vector potential A along a curve C
where dr is a vector line element
Note 1 to entry: For a closed curve C, the protoflux is equal to the magnetic flux Φ through an arbitrary surface S limited by the curve C
where B is the magnetic flux density and endA a vector surface element of S (see IEV 121-11-21).
Note 2 to entry: The coherent SI unit of protoflux is tesla, T = s−2 kg A−1.