Which format is NOT commonly associated with XML data in GIS?

The correct answer is associated with the fact that JSON, or JavaScript Object Notation, is not an XML-based format. While it is commonly used for transferring data, especially in web applications, it does not share the XML structure or syntax.

On the other hand, KML (Keyhole Markup Language) and GML (Geography Markup Language) are both XML-based formats designed specifically for geospatial data representation. KML is used primarily for visualizing geographic data in applications such as Google Earth, whereas GML is used for the encoding of geographic features and geospatial information.

The term GDB Schema relates to the schema definitions used in a Geodatabase, which can leverage XML to define the structure of spatial data. Thus, the emphasis on XML formats in GIS makes KML and GML relevant, while JSON does not fit this classification due to its non-XML nature.