If one creates a pp. 2-0 text field containing the Score/Part insert on the score, it will automatically appear in all linked parts. I don't think a script is needed if one simply uses or creates a template containing this field for one's score.

There is no single template that accommodates my workflow, which consists of a wide variety of projects from around the world. I need to do this for most of the scores I create. It should be in the default document used by the Setup Wizard, but it's not.

I did find an answer to my question - I needed to use dropdown syntax...

last line:

***********

select dropdown "Right" near "Horizontal:"

************************

You can make and save a template of your own. A script is overkill. You can also customize the default file.

I have to do this often, and often in files that I have not created, so therefore it's useful, regardless of your comments to the contrary.

Both of your suggestions are incorrect as methods to incorporate the needed modification into a document created with the setup wizard.

The feature that actually does the job is a "Document Style."

I learned that I can put a usefully-configured document - possibly one I've already made the desired customizations to, regardless of the fact that it contains a finished score - into the Document Styles folder (wherever that's defined to be) and it will show up in the center panel of the Setup Wizard during document setup.

Given that every score I have to do is different, the setup wizard is the most efficient way to create a new document in the general case... not a template, which I would have to create for every new score type.