Yes there is and I use it all the time. For details see the “Load” command in the “GENerel Language Reference” help in GEDitCOM Editor To see it in action, open the web site extensions.
You can also mix loading subroutines from files with subroutines in the internal script. When writing the web site script, I started with them in the main script. Once each section was done, I split that out to separate files. That extension loads multiple files with subroutines.
There is currently no way to have a repository of scripts (like a python module) that all extensions could use, but you can emulate that by just including a module of subroutines in each extension. In other words, the “Load” command only looks for subroutine files within the extension itself Maybe I should change that in the future to store subroutines in folder with the python module too.
Regards,