I've produced a PDF file with PTXprint. When I open it with Firefox on my desktop, Firefox displays the title of the PDF file in the browser's UI, where the tab title is. In my case, it is displaying the tab title "[Unknown] - ABC_Default_MAT_ptxp.pdf". Chrome has similar behaviour. It displays the title "[Unknown]" in the tab title. It also displays "[Unknown]" in the upper toolbar of the built-in PDF viewer.
I confirmed that this is the title of the PDF file by running this command:
$ exiftool public/pdf/AEB2_website_1CO_ptxp.pdf | grep Title
Title : [Unknown]
How do I change this title? I don't want the title to be "[Unknown]", I would like it to be something more user-friendly, so that people who open the PDF file in their browser or in their PDF reader won't see this confusing title in the wrong language.