Original sentence: (In the 1987 IUPAP Red book, for example, this constant was still called permeability of vacuum.Another, now rather rare and obsolete, term is "magnetic permittivity of vacuum".The term "magnetic constant" avoids the term "permeability" and "vacuum" because it is a defined value, not the result of experimental measurement, and is not tied to the properties of the vacuum.The term "vacuum permeability" (and variations thereof) remains very widespread, but standards organizations have recently been moving towards "magnetic constant" as a uniform term for this quantity.The vacuum permeability' is the magnetic constant μ0 (also called the permeability of free space),  a universal physical constant, relating mechanical and electromagnetic units of measurement
Edited sentence: A now rather obsolete term is "magnetic permittivity of vacuum".Currently the nomenclature in physics is magnetic constant.In the 1987 IUPAP Red book this constant was called permeability of vacuum.The magnetic constant μ0 (equal to the vacuum permeability, also known as the permeability of free space) is  a universal physical constant, relating mechanical and electromagnetic units of measurement.The term "magnetic constant" avoids the term "permeability" and "vacuum" because it is a defined value, not the result of experimental measurement, and is not indicative of the properties of the vacuum.The vacuum permeability μ = μrμ0 is equal to μ0