A JSONiq main module is made of two parts: an optional prolog, and an expression, which is the main query.

Figure 2. MainModule

The result of the main JSONiq program is the result of its main query.

In the prolog, it is possible to declare global variables and functions. Mostly, you will recognize a prolog declaration by the semi-colon it ends with. The main query does not contain semi-colons (at least in core JSONiq).

Global variables and functions can use and call each other arbitrarily, even if the dependency is further down in the prolog. If there a cycle, an error is thrown.

JSONiq largely follows the W3C standard regarding modules. The detailed specification is found here.