I use extensively the annotations of PDF files, especially the Highlight type.
More precisely, I use the annotation "subject property".
I'm using it to identify each annotation with many subjects.
For example, I can write the following subjects in the subject property of a specific annotation:
scientific method; scientific truth; Karl Popper; testability; confirmation;
As you can see, I separate each subject with a semicolon and each annotation has many subjects.
Keep in mind that I work with dozens of PDF files, so I have hundreds of annotations and hundreds of topics.
The problem is that I do not know of any PDF software that can extract these topics and present them in alphabetical order so that I can track my topics. I can search within comments but it is not sufficient since I have to remember each subject by hearth or to write them down on a paper.
Karl Popper (56)
scientific method (103)
scientific truth (75)
Do you know the existence of such a script or a similar script which I can modify?
That is something that will have to be custom-developed for your needs. I've created very similar scripts for my clients in the past, and would be happy to work on this project for you. Feel free to contact me (try6767 at gmail.com) if you're interested in hiring someone to do it for you.