Page 339 on the GDL Reference Guide says:
This refers to the custom fields you can define in the "Transmittal Set Scheme" Dialog (called "Issue Scheme" Dialog prior to Archicad 24 - "MarkUp" was renamed to "Issue", and "Issue" was renamed to "Transmittal Set" in Ac24).
The Transmittal Set Dialog opens from the Book Settings Dialog, and the Transmittal Set Scheme Dialog opens from the Transmittal Set Dialog.
In the Transmittal Set Scheme Dialog, you can define custom fields (which can be displayed as Autotext later).
The first 4 fields are default and cannot be deleted. So the GLOB_ISSUE_SCHEME global variable, which I suppose is in the format of
GLOB_ISSUE_SCHEME
returns the names and values of these fields as described in the GDL Reference Guide. The first column is Revision ID, then the 4 default Transmittal Set Scheme Dialog fields, then the custom fields you define.
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