Global data is not tied to any page. To create it you need to create an editor through a special syntax:

---- struct global ----
schema: someschema
----

This creates a table of all global data currently stored in the schema. Existing data can be edited through Inline Editing or deleted through the trash can button. New data rows can be added through the form below the table.

The struct global syntax accepts most of the Aggregation syntax (struct value output does not work with global data, summarize/row numbers is disabled for global data). However, you can specify only one schema you want to edit as global data. All of this can still be done in normal aggregations of course (without the add and delete feature then).

Note: Also see the section Schema Usage for general informations on struct data.