Each zone you create in your project is assigned a Zone category in the Zone’s Settings dialog box. Zone Categories are ARCHICAD attributes.
This Zone Category defines:
•the color of the zone background, and
•the type of Zone Stamp object used for the zone.
The main function of zone categories is to use colors to visually distinguish different types of spaces in your project: for example, you can assign the “Office” category to all your office space, which will all be displayed in pink; and the “Communication and Access” category to the hallways, which will all be displayed in white.
However, you have great flexibility in the display of zone fills.
See 2D Display of Zone Backgrounds.
Some Zone categories are predefined in ARCHICAD; you can define your own categories at Options > Element Attributes > Zone Categories.