Définition
While the concept of urban unit is based solely on the criteria of continuity of habitat, the definition of industrial or urban population zones (ZPIU) corresponds to a broader concept which also takes account of daily commuting levels, the size of the non-farming population and the number and size of industrial, commercial and administrative establishments.
By definition, each urban unit belongs to the same single industrial or urban population zone.
Remarque
The concept of industrial or urban population zone was used for the last time on the occasion of the publication of the 1990 population census.