The width is a measurement that many manufactures use although it isn’t used on an international basis.
In the English table you must bear in mind that a size 4 corresponds to a continental 37.
We may consider this measurement as an approximate reference to determine shoe sizes although it is only carried out at one particular position on the fitting (see picture: volume or metatarsus width), it could be possible for narrower size to be wider than a wide one. This is because the fitting doesn’t just depend on the width at this particular point but it is also influenced if the size is longer or less long, more or less curve and it also depends on the width at other positions of the fitting.
Therefore we may use it as a reference but it is not 100% reliable.
The widths that we show in our catalogues and in the professional area show the width of our shoe with the insole incorporated, this means that the shoe would be even wider if the insole were removed or the width would decrease if a thicker insole were used.