Bluebeam Support informed me that external scripting is a provided feature but not a supported feature so the only avenue for support is peer support. Searching the forum doesn't yield many results that would indicate many users are taking advantage of this feature but I guess that isn't surprising since it isn't supported. The external scripting documentation can be found here:
Bluebeam Script Reference
My issue is in trying to use the external script to modify a markup. Both the ColumnDataSet and MarkupSet commands return an "Invalid Token" error. A web search turns up references to Bluebeam Sessions Invalid Token errors related to insufficient permissions so I'm wondering if there is some permission that needs to be set in the file to allow external script modifications. Has anyone here ever actually successfully used ColumnDataSet or MarkupSet in an external script?