Wiktionary
subzone
n. A zone making up part of a larger zone.
Wikipedia
Subzone
The Subzone is a fictional place used as part of Subway's Subway-Kids.com's ad campaign aimed toward young audiences. It is mostly used as a residential area for the Subway Kids who themselves are spokespeople for the campaign. The sub in Subzone is a reference to Subway or Submarine sandwiches. The Subzone campaign on subway-kids.com, as of March 2007 has been abandoned.
Usage examples of "subzone".
The village of junked cars was especially odd, because farther on was a hillside of uninhabited housesprobably a quarantine order, or a subzone in the making.
The very motion of the earth, its tides and shifting subzones, are related to the moon.