Okay, the Trust ‘unkown’ issue I mentioned in my last post was probably just a small hang-up. I tried it again and cloning a global report worked fine.
Because as mentioned, the steps in the report-format-HOWTO are somehow not applicable to my setup, I followed a different approach:
By cloning a global report, a new directory is set up in which the new custom report lives. This workspace is created not where the global reports are stored but in the user space. In my case this is:
/usr/share/openvas/openvasmd/report_formats/<user_id>/<report_format_id>/
Here you can find the generate script and the XSLT file which describes the layout. In this workspace you can now customize the report format to your specific needs. The XSLT file describes the layout and how the XML report shall be processed. The generate script is like a makefile and specifies how the report output file shall be created.
When a get_report request is made, the Manager calls the generate script and passes the report in raw XML report as argument.